Diseases of Cats 43rd Annual Gross Pathology Course CL Davis Thompson Foundation

Transcription

1 Diseases of Cats 43rd Annual Gross Pathology Course CL Davis Thompson Foundation Brad Njaa, Professor Kansas State Veterinary Diagnostic Laboratory Department of Diagnostic Medicine/Pathobiology Kansas State University Manhattan, KS # Slide Description Diagnosis 1 Cat: 6 month old, upper respiratory signs MDx: Suppurative rhinitis/sinusitis Cause: Streptococcal spp.; associated conditions include otitis media, possibly otitis interna; Note the lack of meningitis in this example. 2 Cat: aged, sagittal section of skull MDx: Intranasal, obstructive neoplasm Comment: the location and white to tan, infiltrative and expansile growth is typical for lymphoma 3a Cat: 12 yo tabby, lateral view of skull Description: Prominent swelling over the frontal sinus. This swelling could have many different causes. Cytologic examination of FNAs found malignant lymphocytes 3b Cat: same as in image 3a, longitudinal section through the skull MDx: Lymphoma, intrasinus and intranasal with erosion or obliteration of sinus bones and turbinates 4a Cat: pluck MDx: Granulomatous pneumonia, severe, MF to coalescing nodules Condition: Lipid pneumonia Histology: accumulation of macrophages, multinucleated giant cells with intracytoplasmic lipid or cholesterol clefts; type II pneumocyte hyperplasia Cause: Inhalation of oily or fatty substances or accumulation of endogenous lipid in alveolar macrophages; pneumocyte proliferation may be associated with excess surfactant production rich in cholesterol which become phagocytosed by alveolar macrophages 4b Cat: middle-aged, right lateral view of thorax and cranial abdomen Description: all lung lobes have raised, tan, firm, coalescing nodules. Lungs failed to collapse. Condition: Lipid pneumonia. Confirmation requires histologic examination of the lung to prove no organisms are present in the macrophages 5 Cat: middle-aged, lungs Condition: Lipid pneumonia; fewer and smaller nodules with less affected lung; endogenous lipid pneumonia is typically an incidental finding at autopsy. This is the more common presentation. 6 Cat: middle-aged, lung, close up Condition: Lipid pneumonia Comment: represent subpleural, intra-alveolar accumulations of foamy macrophages and MNGC; incidental but common finding; frequently seen in cats (and ferrets) 7 Cat: opened thoracic cavity, left lateral MDx: Torsion with infarction of the right middle lung lobe Comment: Typically involve the right middle lung lobe in cats and dogs related to the narrow waist at the hilus; commonly have pleural effusion 8 Cate: pluck removed from the chest, MDx: Marked lung lobe congestion, edema and enlargement with areas of pallor (necrosis); Evidence of pleural thickening suggesting pleural effusion; partial torsion without evidence of complete tissue death 9 Cat: Left lateral, opened thorax with pluck in situ MDx: Chylous effusion with compressive atelectasis and pleural thickening Confirmation: "milky", high triglyceride and lymphocyte count in fluid; Comment: seen in cats, rarely in dogs

2 10 Cat: left lateral, opened thorax with pluck in situ Pathogenesis: most cases are idiopathic; may be associated with: cardiomyopathy, vena caval thrombosis, thoracic masses, dirofilariasis, diaphragmatic hernia, lung lobe torsions, traumatic rupture of thoracic duct MDx: fibrinous hydrothorax or fibrinous pleural effusion with compressive atelectasis, visceral (and parietal) pleural thickening and fibrinous pleuritis Condition: Feline infectious peritonitis (pleuritis) Cause: Feline coronavirus 11 Cat: right, dorsal, lateral view of thorax MDx: Pyothorax (severe, suppurative pleuritis) Comments: given cats propensity to fight and having sharp, long claws as well as long, sharp canine teeth, severe suppurative exudate will develop in the thoracic cavity 12 Cat: right lateral view of thorax MDx: Pyothorax Cause: often reflects bacteria found on the skin or in the oral cavity: P. multocida, Clostridium spp., Fusobacterium spp., Actinomyces spp., and Mycoplasma spp. Additionally, nonoropharyngeal pathogens may be isolated including streptococci, staphylococci, Gram-negative enteric bacteria can commonly be isolated. 13 Cat: pluck MDx: Suppurative, pleuritic with focal necrotizing pneumonia Comment: another common cause of this condition can be migration of foreign bodies such as grass awns. 14 Cat: pluck MDx: Necrotizing bronchopneumonia Comment: pathogenesis is typically aerogenous and most often bacterial. Cause may include aspiration. Bacterial causes include Bordetella bronchiseptica, streptococci, P. multocida, staphylococci, E. coli or anaerobes. This particular case was not cultured so a definitive cause was never confirmed. 15 Cat: right lateral view of thorax and abdomen; 12 yo MC DSH MDx: Multifocal to coalescing pulmonary fibrosis with lobular collapse Condition: Feline idiopathic pulmonary fibrosis (FIPF) 16 Cat: pluck from cat in image 15 Comment: there is more severe and diffuse fibrosis affecting the left lung compared to the patchy fibrosis in the right lung. Pathogenesis: Undetermined. In some cases, there can be concurrent pulmonary carcinoma so difficult to definitively determine grossly. 17 Cat: pluck, 8 yo DSH Comment: another example of FIPF; lesions include interstitial fibrosis, smooth muscle hypertrophy, airways and alveolar filled with foamy macrophages and MNGC, variable nodules of lymphocytes and plasma cells in the interstitium, increased mucus production. 18 Cat: left lateral view of thorax Condition: Feline idiopathic pulmonary fibrosis 19 Cat: Pluck MDx: Severe, alveolar emphysema Comment: distinguishing between emphysema of alveoli and over inflation is dependent upon destruction of septa; This particular case was due to air trapped as a result of a partially obstructive pulmonary carcinoma 20 Cat: right lateral view of thorax (experimental case of cytauxzoonosis, Dr. Panciera) MDx: MF pulmonary hemorrhage with congestion and edema Cause: Cytauxzoon felis, tick transmitted (ixodid ticks) Pathogenesis: Tick bite > C. felis infection > acutely febrile > death (nearly 100%) in days Lesions: icterus, dark urine, dyspnea, multifocal pulmonary hemorrhage, splenomegaly Microscopic: numerous schizont-containing bacteria in nearly every tissue, especially spleen, liver, lung 21 Cat: dorsal view of pluck Comment: Another example of cytauxzoonosis 22 Cat: left lateral thorax MDx: multifocal pulmonary necrosis with hemorrhage and regional consolidation; icterus; multifocal hepatic necrosis Cause: Francisella tularensis (causative organism for tularemia)

3 Comment: multifocal pulmonary necrosis is a minor change; foci of necrosis in the liver, spleen and lymph nodes are more diagnostically relevant for this disease. 23 Cat: dorsal view of pluck MDx: multifocal to coalescing pulmonary granulomas Insert: BANG lesions (Bronchiolitis, abscess, neoplasia, granulomas). Therefore, there is nothing pathognomonic about this lung. Cause: Aelurostrongylus abstrusus Life cycle: eggs are coughed up and swallowed by the cat host, passed in feces and ingested by snails and slugs (intermediate hosts). Birds, rodents, frogs and lizards (paratenic hosts) eat the invertebrates. Cats complete the life cycle by ingesting either intermediate or paratenic hosts. Comment: relatively common lungworm of cats; live in terminal and respiratory bronchioles; granulomatous inflammation to the parasites and eggs result in nodule formation 24 Cat: right lateral thorax MDx: Granulomatous pneumonia Cause: In this particular case, this was caused by Histoplasma capsulatum. This is virtually pathognomonic for histoplasmosis, however, other fungi could cause a similar lesion. 25a Cat: right lateral thorax and abdomen MDx: Multifocal pulmonary and hepatic granulomas (alternatively, granulomatous pneumonia and hepatitis) Cause: Histoplasma capsulatum 25b Cat: right lateral thorax and abdomen Comment: his is another version of histoplasmosis. Larger coalescing areas of granulomatous inflammation. 26 Cat: dorsal view of pluck Comment: Granulomatous pneumonia formation more of a lattice or reticular pattern giving the appearance of inflammation primarily confined to the pulmonary interstitium. 27 Cat: dorsal view of lung, 5 month old cat MDx: pulmonary mineralization, multifocal to coalescing, regionally diffuse Comment: morphologically, this looks very similar to lipid pneumonia, however, the lung would feel firm, appear to fracture when palpated and feel very gritty against the knife when sectioned. Pathogenesis: mild interstitial mineralization is referred to as uremic pneumonitis related to chronic renal disease and secondary renal hyperparathyroidism. Summary: multisystemic mineralization due to intoxication with rodenticide containing cholecalciferol (vitamin D3) Quintox, Ortho Rat-B-Gone, True Grit Rampage. 28 Cat: right lateral thorax MDx: Pulmonary carcinoma Comment: the lungs location between the heart and rest of the body provides a filter function, therefore, any tumor can potentially metastasize and lodge in the lung. The most common are carcinomas (mammary especially), melanoma (rare in cats) and hemangiosarcoma (uncommon in cats). 29 Cat: dorsal view of pluck Description: multiple, firm, variably umbilicated nodules with a larger mass in the cranial portion of the left lung lobe. Comment: because of its dual circulation, primary lung tumors can also metastasize to the lung. In this case, the primary tumor is in the cranial portion of the left lung and the remaining nodules are metastatic. 30 Cat: left lateral thorax Description: multifocal nodules throughout the lung with evidence of similar nodules on the parietal pleura and pleural surface of the diaphragm. If only surface orientated, this may represent mesothelioma. With infiltration of the lung, this is more typical for metastatic carcinoma with carcinomatosis. This particular case is metastatic mammary carcinoma. The majority of mammary tumors are malignant and they have a tendency to metastasize to the lung as well as regional lymph nodes.

4 31 Cat: opened thorax, same cat as image 30 Description: pleural effusion with carcinomatosis of the parietal pleura as well as metastatic neoplasia to the lung 32 Cat: ventral view of thorax Description: multilobulated, cranial mediastinal mass. Diagnosis: thymoma with compressive atelectasis 33 Cat: pluck from same cat in image #32 MDx: Cystic thymoma Comment: typically occur in middle-aged to older cats; simplest, historical classifications have been lymphocytic, epithelial or mixed. Cat thymomas are often cystic. For more detailed classification of types, refer to JK&P 6 th Vol. 3, pg Cat: ventral view, head, neck, upper thorax Description: lymphadenomegaly, multicentric Comment: Grossly, this could represent severe systemic infection or lymphoma. This particular case was a cat with systemic mycobacteriosis (atypical mycobacterium). The cat presented with near complete alopecia and was extremely emaciated. She had been treated for months with corticosteroids. Lymph node sections were filled with macrophages laden with mycobacteria. 35 Cat: mesenteric lymph nodes, mesentery and intestine MDx: necrotizing lymphadenitis Cause: Francisella tularensis This photo was taken by Dr. Roger Panciera from Oklahoma State University. Oklahoma and Kansas are a hot bed for Tularemia. Focal necrosis affecting lymph nodes, spleen and liver is an endemic region typically in the spring, summer and fall months is considered tularemia until proven otherwise. However, it is indistinguishable from Yersiniosis. 36 Cat: cross section of lymph node from image #35 Description: multifocal to coalescing areas of necrosis with prominent cortical and medullary edema 37 Cat: right lateral thorax MDx: mediastinal lymphoma with marked compressive atelectasis. Any and all lymphoid tissue in the cat is a potential site for lymphoma to originate. At this stage, this could represent thymic lymphoma or lymphoma arising from mediastinal lymph nodes. Histology required to try and differentiate. 38 Cat: ventral view of pluck from cat depicted in image #37 Comment: cross section of mass depicts areas of hemorrhage and necrosis 39 Cat: spleen, 16 yo DSH Description: multiple nodules bulging from the surface with the largest being dark, hemorrhagic and clotted blood is present on the surface arising from a ruptured capsule. Diagnosis: Hemangiosarcoma Comments: HSA is very rare in cats. Gross features minimally vary from HSA in dogs. These neoplasms will spread to the lungs in cats similar to dogs. 40 (a&b) Cat: spleen MDx: disseminated, granulomatous splenitis Cause: Histoplasma capsulatum Insert: in slide a, which is the head of the spleen and which is the tail? Anatomic books that I have searched do not address this terminology. This is an imaging, ultrasound terminology and surgeons are taught that the tail of the spleen represent the portion of spleen less firmly attached to the stomach, therefore, the tail of the spleen is the end with the largest diameter. Comments: in slide b, there is a complicated gross appearance. Some of the nodules observed are granulomas, some are lymphoid hyperplasia and there may even by aggregates of EMH. 41 Cat: Abdominal cavity MDx: necrotizing splenitis and hepatitis (very mild in this image) Cause: Francisella tularensis 42 Cat: spleen (Roger J. Panciera) MDx: Multifocal, necrotizing splenitis Comment: This is one of my favorite images depicting tularemia. 43 Cat: heart and lungs Comment: This is not a disease or lesion but a common finding in cats euthanatized by intracardiac injection. It is unclear if this represents the drug or a localized chemical reaction to the carrier but it is very common. Corresponding plaques will be observed on the epicardial surface of the pericardium. Confirmation this is an

5 artifact of euthanasia: strong odor of alcohol from the epicardium or pericardial sac contents. 44 Cat: heart and aorta and brachycephalic trunk (from cat whose lungs are depicted in image #27) MDx: Aortic mineralization (aortic arteriosclerosis) Comment: histologically, subendothelial degeneration and mineralization of large vessels 45 Cat: 6 yo DSH, opened heart and aorta MDx: Ventricular septal defect with (secondary) right ventricular hypertrophy and dilatation 46 Cat: ventral view of thorax, abdomen and heart, removed from pericardial sac Description: very marked cardiomegaly MDx: Hypertrophic cardiomyopathy Comment: the late Dr. King used to preach that cat hearts should weigh less than 17 gms. I tend to obey that edict with the modification of 17 gms for cats other than Maine coon cats. Not easy to tell in this photograph, there does appear to be pulmonary congestion and the liver has an accentuated reticular pattern suggesting bi-ventricular heart failure in this case. Cause: autosomal dominant disorder (mutation of the cardiac myosin binding protein C (MYBPC) protein) of Maine Coon and Ragdoll cats and American shorthair cats; can also be secondary to hyperthyroidism Lesion: both genetic and hyperthyroid forms cause concentric myocardial hypertrophy 47 Cat: longitudinal section of heart Condition: hypertrophic cardiomyopathy Comment: this is a great method for depicting the marked left ventricular hypertrophy relative to the right ventricles and the atria. Both left and right atria appear moderately to severely dilated. 48 Cat: cross section of heart from image #47 Comment: for the purposes of the photograph, the right ventricle remains attached such that the heart is folded to depict relative ventricular thicknesses but can be returned to normal alignment for photographs. 49 Cat: heart, longitudinal section MDx: Hypertrophic cardiomyopathy Comment: another example of the same condition; note the markedly dilated left atrium in this example. 50 Cat: ventral view of heart Condition: dilated cardiomyopathy Lesion: dilatation of all 4 chambers of the heart Cause: taurine deficiency Disease: Taurine-deficiency myocardial failure (TDMF) Pathogenesis: taurine is an essential amino acid in cats important for modulating Ca++ influx in myocardial cells. 51 Cat: heart, opened left ventricle Condition: endocardial fibrosis Comment: This may represent restrictive cardiomyopathy otherwise referred to as left ventricular endocardial fibrosis. May be sequela to previous endomyocarditis with some speculation that Bartonella spp. play a role. Condition is typically seen on older cats. 52 Cat: 3 yo M DSH, pluck with heart removed from pericardial sac 53 Cat: pluck, left lateral with opened right ventricle and right atrium 54 Cat: caudal abdomen, opened distal aorta and femoral branches MDx: Myocardial hemorrhages and pulmonary congestion and edema with hemorrhages Comment: in concert with icterus, the correct time of year and in an endemic region, tularemia would need to be a top differential diagnosis. However, this lesion could represent septicemia or other bacterial causes of myocarditis. MDx: Moderate to marked pulmonary congestion and edema with locally extensive hemorrhage and intra-right atrial nematode Condition: dirofilariasis Cause: Dirofilaria immitis Description: Vascular thrombosis of the distal aorta and femoral branches Condition: Saddle thrombus Comment: reportedly, 1/3 of cats with hypertrophic cardiomyopathy will develop either unilateral or bilateral thrombi 55 Cat: whole cat Condition: saddle thrombus of the distal aorta with unilateral hindlimb ischemia

6 56 Cat: right lateral of opened abdomen and thorax Comment: right footpads are dark red and dry compared with the normally pink, foot pads. Commonly, the ischemic limb is cooler than normal and it is difficult or impossible to detect a femoral pulse on the affected sides. MDx: peritoneopericardial diaphragmatic hernia (PPHD) with hepatic lobe herniation into the pericardium. Referred to by some as the most common congenital pericardial anomaly in cats. Many times, these are identified as incidental findings based on imaging but are usually diagnosed in the first year of life. Condition: PPHD 57 Cat: caudal, right lateral view of abdomen and thorax, 58 Cat: liver Comment: this is the liver from a case of PPHD with a lobe or portions of lobes atrophic and misshapen relative to the remainder of the liver and a darker red with presumptive fibrosis. 59 Cat: liver with intact common bile duct and attached stomach, duodenum and pancreas 60 Cat: liver with intact common bile duct, opened gallbladder and attached stomach, duodenum and pancreas Description: dilated gall bladder with some distortion and lack of normal bile color Comment: the gall bladder contains abundant mucus and is modestly dilated with some biliary liths intraluminally. This is the only case of a biliary mucocele I have seen in a cat. 61 Cat: liver with malformed gallbladder Comment: cats seem to have a propensity for various, malformed gallbladders. Care must be taken to determine if the malformation is a congenital change or acquired due to obstructive disease. In this case, the animal is icteric and there is presumptive obstruction. A definitive obstruction was never confirmed in this case. 62 Livers from cat (x2), dogs (x1) and woodchuck (x1) (This is from Cornell and is possibly a John King photograph or one of his trainees.) Comment: This is a fun photograph that depicts livers from cats and other species depicting common changes. The pale liver is a cat with severe, diffuse lipidosis whereas the other liver on top represents as normal cat liver. The lower left liver is from a small breed dog depicting hepatic atrophy, nodular regeneration and fibrosis (ie. Cirrhosis). Finally, the lower right liver is from a woodchuck and depict a hepatocellular carcinoma. This is caused by hepadenavirus. This was first discovered in Ithaca by collaborative efforts between the late Dr. King and Dr. Bud Tennant after they were finding a large number of woodchucks with hepatocellular carcinomas. It became the prototypic virus for Hepatitis B in people. 63 Cat: ventral view of liver, intestines, kidney Comments: this represents HANG (hyperplasia, abscess, neoplasia, granuloma) changes in tissue. This particular case is nodular hyperplasia but would require histologic examination in order to be definitive. 64 Cat: liver, diaphragmatic surface view MDx: Multifocal, hepatic necrosis/necrotizing hepatitis, multifocal Cause: Francisella tularensis Comment: as mentioned previously, this is so long as other things fit such as region, similar nodules in spleen and/or lymph nodes. It may also represent yersiniosis. 65 Cat: liver, abdominal view MDx: hemorrhage cystitis with hepatic lymphadenitis Comment: anything that could cause cystitis and lymphadenitis must be considered and additionally, based on this photograph, the gallbladder changes may be associated with obstruction by the changes in the lymph node, and therefore, lymphoma must be a consideration. Diagnosis: Toxoplasma lymphadenitis, cystitis and hepatitis Additional comments: Toxoplasmosis is a suppurative and necrotizing lesion. 66 Cat: liver, dorsal, diaphragmatic view Condition: ductal plate malformation (formerly biliary cyst adenoma) Comment: The new JK&P refers to these as Von Meyenburg complexes, representing malformations arising from persistent embryonic ductal plate remnants. Histologically, there are irregular-shaped, branching, biliary ductular structures lined by cuboidal to flattened epithelium.

7 67 Cat: liver, dorsal, diaphragmatic view Condition: ductal plate malformation/von Meyenburg complexes 68 Cat: liver, two sections, one stained with iodine Comment: staining with iodine is a very effective method for highlighting the present of amyloid in tissue. 69 Cat: 14 yo FS DSG, liver MDx: cholangiocellular carcinoma with hepatic atrophy Comment: This liver and proliferative mass occupied around 2/3 s of the abdominal cavity. Masses are mostly bulging. 70 Cat: 12 yo FS DSH, liver, abdominal surface MDx: cholangiocellular carcinoma Comment: This tumor metastasized to the lung. Note that a few of the neoplastic nodules depict umbilicated centers. 71 Cat: 14 yo FS DSH, liver, diaphragmatic surface MDx: cholangiocellular carcinoma Comment: This depict bulging proliferation as well as areas with central umbilication. The surrounding liver is pale suggestive of hepatic lipidosis. 72 Cat: liver, diaphragmatic surface MDx: metastatic carcinoma Comment: there is no difference between this gross depiction of neoplasia and the previous. The tumors are more red but depict bulging as well as umbilication. This is the liver from a cat with pancreatic exocrine carcinoma. Liver pallor also suggests hepatic lipidosis. 73 Cat: ventral view, opened abdomen Description: marked splenomegaly, diffuse and multifocal pale hepatic parenchymal nodules with a diffusely enhanced reticular pattern Comment: This is indicative of infiltrative neoplasia. The tail of the spleen has been incised and is not exuding blood, therefore, this spleen is meaty and likely infiltrated. This was diagnosed as lymphoma but other considerations include visceral mast cell tumor and possible plasma cell tumor. 74 Cat: dorsal surface and tip of tongue MDx: eosinophilic granuloma with ulceration Comment: eosinophilic granuloma complex likely represents a nodular hypersensitivity disease 75 Cat: 18 yo, ventral view of oral cavity including soft and hard palate and lip MDx: Squamous cell carcinoma Comment: these can arise from the buccal gingival or from the tonsil; these are highly infiltrative and rapidly growing. The often invade bone in severe cases. 76 Cat: stomach, opened MDx: gastric mucosa and submucosal mineralization Comment: this is the stomach from the cat observed earlier with pulmonary and aortic mineralization. Cause: vit D3-containing rodenticide ingestion and intoxication 77 Cat: stomach and duodenum MDx: Gastric lymphoma Comment: the serosal surface is severely distorted and discolored due to the diffuse infiltration by neoplastic lymphocytes. The mucosal surface was similar distorted and regionally ulcerated. Other neoplasms would be unlikely for this particular lesion. 78 Cat: small intestine, mesentery and mesenteric lymph nodes Description: severely plicated loops of bowel Comment: this morphologic feature is virtually pathognomonic for a linear foreign body in the lumen of the small intestine. Over time, if the foreign body is thin like thread or dental floss, the repeated peristaltic waves can result in intestinal perforation. 79 Cat: partially opened abdominal cavity MDx: segmental intestinal congestion with minimal mural hemorrhage Comment: Feline panleukopenia is caused by parvovirus and often results is segmental intestinal lesions grossly and histologically. Histology: loss or epithelial atrophy of crypts of Leiberkuhn with dilation, cellular debris and villous atrophy. This lesion is called radiomimetic because it mimics the effects of radiation injury to regenerative epithelium in the intestine. 80 Cat: right lateral view, opened abdomen MDx: Fibrinous peritonitis Cause: Feline coronavirus Comment: this image is considered virtually pathognomonic for the wet form of feline infectious peritonitis (FIP). However, a

8 penetrating foreign body or possibly bacterial septicemia would have to be considered. 81 Cat: small intestine MDx: Granulomatous serositis, peritonitis, mesenteritis and vasculitis Comment: histologically, this will likely be pyogranulomatous but grossly it appears more granulomatous. Several of these nodules follow the serosal and mesenteric blood vessels. 82 Cat: ileum, opened with exposed Peyer s patch 83 Cat: opened abdomen and thorax, ventral view MDx: Peyer s patch necrosis/lymphoid necrosis of ileal Peyer s patches with multifocal intestinal hemorrhage and necrosis Comment: given that lymph nodes and spleen are targeted when cats are infected with Francisella tularensis, it is not unexpected to have Peyer s patch necrosis with Tularemia. MDx: megacolon/marked colonic distension Comment: a definitive cause is not established by an abnormality in smooth muscle function may be the underlying cause; it may also be tied to developmental abnormalities to the innervation of the bowel. This is often referred to as idiopathic megacolon. 84 Cat: intestine, focal mass Disease: Intestinal lymphoma Comment: in cats, there is a continuum between inflammatory infiltrates in the intestine and small cell lymphoma (T cell lymphoma). Differentiation requires experience as well as use of new molecular techniques (PCR clonality). Large-cell lymphoma of the intestine tend to be high grade neoplasms (high mitotic index and infiltrative growth) that efface normal intestinal architecture. They can become obstructive by partially or completely occluding lumens. 85 Cat: duodenum, omental fat and pancreas MDx: pancreatic congestion and edema with peripancreatic fat necrosis Comment: This suggests that has been pancreatic enzyme leakage with fat necrosis and likely saponification. The underlying cause is often undetermined. 86 Cat: pancreas, intestine MDx: Chronic pancreatitis with fibrosis Comment: the pancreatic fibrosis is evident which then implies previous episodes of pancreatitis. It may be smaller than normal but that is an equivocal finding. 87 Cat: stomach, duodenum and expanded pancreas MDx: Pancreatic carcinoma with carcinomatosis Comment: this is the pancreas from the case shown earlier that depicted multiple neoplasms in the liver that were dark red. A small remnant of pancreas is seen amidst that myriad proliferation nodules in the omentum and on the serosal surface of the proximate duodenum. 88 Cat: liver, stomach, duodenum and pancreas MDx: Pancreatic adenocarcinoma with partial duodenal obstruction Comment: This is focal mass arising from the pancreatic parenchyma. The degree of desmoplasia is supportive of exocrine pancreatic carcinoma, however, an endocrine carcinoma cannot be completely discounted without histologic evaluation. 89 Cat: cerebellum and brainstem, dorsal view MDx: Cerebellar herniation Comment: any reason for increased intracranial pressure may lead to cerebellar herniation. Histology: may be mixtures of hemorrhage and necrosis and degeneration of folia with regional loss of Purkinje cells and granular cells. 90 Cat: brain, dorsal view MDx: Unilateral, atrophy and loss of gyri, left cerebral hemisphere with multifocal hemorrhage Condition: Unilateral ischemic encephalomalacia Comment: This is most common in the mid to late summer months in the Northeast but is not limited to the northeast. Dr. Summers and de Lahunta tried to make a connection with aberrant migration of cuterebra larva. 91 Cat: brain, dorsal view Condition: Unilateral ischemic encephalomalacia

9 Comment: This appears to be more severe in the left cerebral hemisphere but the right hemisphere appears abnormal as well with deeper sulci. This latter change could be an age-related change. 92 Cat: brain, ventral surface near optic chiasm Description: A cuterebra larva is caught in the meninges and appears to be instigating a localized eosinophilic (slightly green) meningitis. 93 Cat: brains, ventral view, normal on left, abnormal on right MDx: cerebellar hypoplasia Cause: in utero feline parvovirus infection Pathogenesis: external granular cell layers actively dividing during cerebellar development are most susceptible to the effects of viral infections which cause selective necrosis in the granular cell layer. 94 Cat: brain, dorsal view MDx: multifocal, meningeal granulomas/granulomatous or pyogranulomatous meningitis Comment: this inflammation tends to course along blood vessels and is affecting the meninges of the cerebrum and cerebellum 95 Cat: brain, dorsal view Comment: This is also FIP but is less vascular orientated and much more subtle. 96 Cat: caudal midbrain MDx: Granulomatous periventriculitis with ventricular occlusion and intraventricular exudate Comment: this can be more subtle grossly if there is a lack of occlusion. This section may also have evidence of meningeal lesions. 97 Cat: cerebrum, at level of optic chiasm MDx: Granulomatous periventriculitis 98 Cat: basal ganglia and lateral ventricles MDx: Granulomatous encephalitis Comment: the lesions regionally have a glassy to gelatinous appearance. In isolation, one would have to consider an oligodendroglioma I suppose. Cause: Cryptococcus neoformans 99 Cat: multiple section, rostral to and including Condition: Cryptococcosis section in image # Cat: Multiple brain cross sections Comment: these section depict areas of more gelatinous, motheaten appearance. This is also an example of Cryptococcosis. 101 Cat: brain, dorsal view MDx: Meningioma with regional cerebrocortical atrophy Comment: these are common, often incidental findings at the time of autopsy. These slow-growing masses slowly lead to compressive atrophy of the underlying CNS tissue, depending on where they arise. 102 Cat: brain, cross sections MDx: Oligodendroglioma Comment: slightly gelatinous and soft appearance with areas of hemorrhage 103 Cat: brain, cerebrum at level of optic chiasm MDx: Astrocytoma Comment: compared to the previous example, this neoplasm appears more firm and dense along with areas of hemorrhage and likely degeneration 104 Cat: longitudinal section MDx: choroid plexus adenoma with hydrocephalus/dilated lateral ventricle Comment: hydrocephalus implies the adenoma is partially obstructive 105 Cat: brain, ventral view with pituitary gland MDx: pituitary adenoma 106 Cat: brain, cross section of brain MDx: pituitary adenoma 107 Cat: spinal cord MDx: spinal lymphoma 108 Cat: pinna and external acoustic meatus (EAM) MDx: ceruminous cystomatosis Comment: these are ceruminous (apocrine) gland proliferations that become ectatic. They can remain on the concave surface of the pinna or extend into the EAM. They have been mistaken for

10 109 Cat: tympanic bullae and oronasopharynx, ventral view 110 Cat: tympanic bulla and oronasopharynx, ventral view, close up of image #109 melanomas since they are often dark blue to black. Abyssinian cats are most susceptible. MDx: bilateral otitis media with nasopharyngeal polyp protruding from the auditory tube Comment: these have been called nasopharyngeal polyps for years and are commonly associated with otitis media, most frequently but no exclusively in cats 3 yrs or younger. Given their association with otitis media, they likely arise from inflamed mucoperiosteum of the middle ear. They remain in the middle ear, pass through the auditory tube into the nasopharynx or may extend into through the tympanic membrane into the EAM. Thus, should be called inflammatory aural polyps. MDx: Otitis media with inflammatory aural polyp Not how red and inflamed the mucoperiosteum of the middle ear looks amidst the suppurative exudate in the lumen. The otitis media is most likely due to a dysfunctional auditory tube. 111 Cat: tympanic bullae, ventral view MDx: otitis media with nasopharyngeal exudate. Young cats that have severe upper airways disease and exudate will almost certainly have otitis media. 112 Cat: globe, longitudinal section MDx: endophthalmitis with retinal detachment Comment: the outer choroid is thickened and pale tan. Therefore, this may represent a case of FIP endophthalmitis. Histology: prominent perivascular inflammatory cuffs in the choroid as well as the retina and anterior uvea 113 Cat: globe, rostral view MDx: scleral nodule Comment: this could represent a solitary neoplastic nodule or a granulomatous nodule must consider the whole animal when making a diagnosis. In this case, it was granulomatous nodule due to systemic histoplasmosis. 114 Cat: globe, longitudinal section MDx: nasal/sinus lymphoma with periocular infiltration and slight compression of the globe 115 Cat: globe, longitudinal section MDx: iridal lymphoma Comment: without histologic evaluation, this could possibly be an amelanotic iris melanoma. Iridal lymphoma is the second most common intraocular tumor in cats. 116 Cat: globe, longitudinal section, both calottes MDx: diffuse iris melanoma Comment: most common intraocular tumor in cats. Many of these are benign. 117 Cat: globe, longitudinal section MDx: intraocular sarcoma, likely post-traumatic Comment: these tumors are likely the result of metaplastic transformation of lens epithelium into malignant mesenchymal cells. Thus, for these to occur, the trauma must disrupt the lens capsule causing it to rupture. These may be strictly fibroblastic or can also transform in mesenchymal cells that produce osteoid. Roughly ¼ of these tumors can be round cell variants and are presumed to be lymphoma. 118 Cat: larynx, trachea, thyroid gland MDx: unilateral thyroid adenoma/adenomatous hyperplasia 119 Cat: tongue, larynx, esophagus, trachea, thyroid gland MDx: unilateral thyroid adenoma/adenomatous hyperplasia with contralateral thyroid atrophy 120 Cat: thyroid gland MDx: unilateral thyroid adenoma/adenomatous hyperplasia 121 Cat: trachea, thyroid gland MDx: thyroid carcinoma with thyroid gland atrophy 122 Cat: larynx, trachea, esophagus, thyroid and parathyroid glands MDx: parathyroid gland hyperplasia Comment: this is likely secondary hyperparathyroidism, most commonly due to renal failure in the cat. 123 Cat: parathyroid, thyroid and paraesophageal MDx: malignant parathyroid tumor with thyroid follicular cyst soft tissue 124 Cat: lion kidney, domestic cat kidney Comment: a cat is a cat; these are both normal kidneys 125 Cat: urinary bladder, ureters and both kidneys longitudinally sectioned MDx: unilateral renal atrophy; intrapelvic renoliths Comment: the late Dr. John King used to refer to this a unilateral renal shutdown. The pathogenesis for this lesion is not understood but it likely reflects some level of vascular compromise. I find this

11 to be extremely common in middle to older cats to find one kidney is smaller than the other. The uroliths in this case may represent dried solidified nephroliths (this is a historic case so cannot be verified but is morphologically consistent). These are palpably hard but lack any crystalline basis and essentially petrified blood. Pathogenesis for this is unclear. 126 Cat: left and right kidneys Comment: this is another more extreme example. Note that the smaller kidney is much smaller, however, the larger kidney is also somewhat asymmetric and malformed. 127 Cat: left and right kidneys Comment: this is an extreme example where the small kidney appears fibrotic and the large kidney appears normal. The large kidney may have undergone compensatory hypertrophy. 128 Cat: Persian, 6 mo, left lateral view, exposed abdominal viscera MDx: polycystic kidney disease Comment: observe that there is evidence of polycystic disease involving not only the kidneys but also the liver and pancreas. Cause: mutations of PDK1 and PDK2, autosomal dominant, which encode for polycystin 1 and polycystin Cat: Persian, 6 mo, kidneys from cat in MDx: polycystic kidney disease image # Cat: kidney, longitudinal section MDx: nephrocalcinosis/renal cortical and medullary mineralization Comment: these are the kidneys from the cat that you have seen the lung (#27), aorta (#44) and gastric mucosa (#76). This could similar, although likely less severely, result from primary hyperparathyroidism or renal secondary hyperparathyroidism. 131 Cat: kidney, longitudinal section MDx: renal papillary necrosis Comment: similar to the horse, the pathogenesis is the same with NSAIDs inhibiting prostaglandin synthesis leading to impaired vascular control and perfusion and subsequent regional ischemia. The region that is normally the least perfused even with prostaglandin effect is the inner medulla. 132 Cat: longitudinal section MDx: pyelonephritis Comment: these are typically due to either ascending or systemic bacteria and chronically can lead to renal scars that may extend from the pelvis to the cortex and capsule. 133 Cat: longitudinal section, view of outer surface and inner surface of cortex MDx: pyogranulomatous perivasculitis/vasculitis Comment: inflammation follows the subcapsular cortical blood vessels but will also extend into the parenchyma 134 Cat: outer surface of left and right kidneys MDx: pyogranulomatous perivasculitis/vasculitis 135 Cat: outer surface, capsule removed MDx: renal lymphoma Comment: these nodules extend into the parenchyma and tend to be more random and less likely to follow the renal circulation 136 Cat: outer surface of left and right kidneys MDx: renal lymphoma Comment: less nodular and more infiltrative with minimal surface bulging compared with kidneys in image # Cat: kidney, longitudinal sectioned MDx: renal lymphoma Comment: the irregular contour of the kidney may be a combination of infiltrative lymphoma and cortical loss due to preexisting renal atrophy of previous renal infarcts 138 Cat: kidney, longitudinal section MDx: renal lymphoma 139 Cat: kidney, longitudinal section MDx: renal adenoma Comment: solitary, expansile but appears partially encapsulated 140 Cat: kidney, cross section MDx: renal carcinoma, papillary with marked compressive renal atrophy Comment: this has an outer rim of fibrosis but it may also represent regional desmoplasia with regional necrosis. 141 Cat: urinary bladder in situ MDx: severe, hemorrhagic cystitis Comment: this presumption is that there is an outflow obstruction. Condition: FLUTD (feline lower urinary tract disease)

12 142 Cat: urinary bladder in situ, opened MDx: Hemorrhagic and necrotizing cystitis Comment: this is a severe case with luminal and mural necrosis 143 Cat: opened and exposed abdomen Description: markedly distended urinary bladder Comment: likely a reflection of dysautonomia. Incidence if low but a few cases have been reported in eastern Kansas. The etiology is unknown. Lesions may include an atonic urinary bladder in addition to megaesophagus. Histology: chromatolytic autonomic and somatic lower motor neurons in the brain stem and spinal cord 144 Cat: urinary bladder and urethra, opened Condition: obstructive urolithiasis due to struvite Control: magnesium-restricted, ph controlling (more acid) diets 145 Cat: 22 yo, urinary bladder, opened with attached ureters and portion of urethra MDx: transitional cell carcinoma (TCC) Comment: TCC is very uncommon cats, especially when compared to dogs 146 Cat: normal fetus with attached placenta Comment: cats have a zonary placenta. The central pink region makes intimate attachment to the uterus whereas the peripheral brown region is the marginal hematoma. This is much less prominent in cats compared with dogs. 147 Cat: fetus with placenta attached MDx: mummified fetus 148 Cat: fetus with attached placenta (courtesy Dr. Gordon Andrews) MDx: epitheliogenesis imperfecta Comment: intact epidermis is present over the pinnae, over the face, and appears intact on the foot pads. 149 Cat: uterus, one horn opened MDx: pyometra with cystic ovary 150 Cat: uterus, one horn opened MDx: pyometra with cystic ovary 151 Cat: uterine horns, partially opened, ovaries MDx: Cystic endometrial hyperplasia obscured by intrauterine polypoid structures 152 Cat: uterus, unilaterally markedly expanded MDx: Cystic endometrial hyperplasia 153 Cat: uterus, centrally incised, distorted MDx: Uterine adenocarcinoma beyond recognition 154 Cat: abdomen opened exposing liver, kidney, MDx: Ovarian adenocarcinoma with peritoneal carcinomatosis ovary and uterus as well as peritoneum 155 Cat: testicle removed from vaginal tunic MDx: granulomatous orchitis and epididymitis 156 Cat: head, neck and shoulders, regional Comment: an emerging cuterebra larva alopecia 157 Cat: subcutaneous tissue over shoulders, skin MDx: Vaccine-associated fibrosarcoma removed 158 Cat: section of skin removed at autopsy Condition: shiny skin alopecia Comment: paraneoplastic integumentary change related to intraabdominal neoplasia Journal of Feline Medicine and Surgery Open Reports July- December 2015 vol. 1 no Cat: palmar surface of forelimbs MDx: Metastatic pulmonary carcinoma Comment: this is the strange paraneoplastic phenomenon in which cats develop metastatic lesions in the toes and nailbeds. First observed as acini lined by cilia surrounded by desmoplasia. 160 Cat: left lateral shoulder, thorax and abdomen MDx: multifocal, folliculitis with hyperkeratosis Condition: Dermatophytosis or ringworm 161 Cat: dorsolateral skin over left shoulder and thorax 162 Cat: lateral view of head and medial view of left forelimb 163 Cat: cytology from lesions of cat depicted in image #162 Description: increased skin fragility Comment: this can be most commonly due to iatrogenic steroid use or endogenous hyperadenocorticism, possibly due to diabetes mellitus, hepatic disease, idiopathic or Ehlers-Danlos syndrome. This particular case was due to the cat being cushingoid. Histology: profound dermal collagen atrophy and remaining collagen fibers of thin and disorganized with marked hair follicle atrophy. MDx: pyogranulomatous dermatitis with marked ulceration and crusting Condition: Sporotrichosis Description: Neutrophils and macrophages with extracellular and intracellular Sporothrix organisms

13 164 Cat: forelimbs MDx: pyogranulomatous dermatitis with ulceration and crusting Cause: Cryptococcus neoformans 165 Cat: right lateral thorax and abdomen MDx: granulomatous dermatitis Condition: mycetoma or opportunistic fungal infections Histology: clusters of fungal hyphae forming variably-sized nodules with numerous macrophages, multinucleated giant cells, lymphocytes and plasma cells Comment: this represents the most severe form of fungal dermatitis likely reflecting an impaired host immune status 166 Cat: subcutaneous view of nodule from cat in MDx: granulomatous dermatitis image # Cat: caudal surface of hind limb MDx: eosinophilic granuloma/plaque 168 Cat: perineum MDx: feline sarcoid Comment: there is no way to know this from this image, however, this is one of two male sibling cats that were neutered on the same day but the same vet using the same tools (kept in cold sterile solution). These tools were also used for surgical removal of tumors from farm animals. Both developed feline sarcoids at the surgical site. A second tumor returned