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Selected Gross Pathology of the Cat
Bruce Williams, DVM, DACVPDept. of Veterinary Pathology
AFIP, Washington [email protected]
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SELECTED GROSS PATHOLOGY OF THE CAT
2009 Gross Morbid Pathology of the Diseases of Animals 23-27 March 2008
Bethesda, MD Instructor: Bruce H. Williams, DVM, DACVP
Dept. of Veterinary Pathology, AFIP (202) 782-2650 Email: [email protected]
PURPOSE The purpose of this 3-hour block of instruction is to gain knowledge and experience in the gross diagnosis of diseases of the domestic cat. (Felix silvestris catus). Of course, the study of disease in this species far exceeds what can be presented in a three hour block of time, but I will attempt to cover a number of diseases of interest. In some cases, inclusion or exclusion from this collection was the result of the availability of high-quality photographs. I am a firm believer that one can learn far more from one excellent photograph of a single entity, than from many poor ones. If the only available image is of poor quality, the image won’t leave a lasting impression, and the student learns nothing. I have included a brief morphologic diagnosis for each entity. The formulation of concise, accurate morphologic diagnoses is a major pursuit of every good pathologist, especially those who seek certification in this specialty. The formulation of a good morphologic diagnosis is a learned skill; for those seeking additional experience in this endeavor, I would suggest attendance at the annual AFIP Descriptive Pathology Course in Washington D.C. .
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Slide No.
Organ Condition Morphologic Diagnosis Notes
1. INTRODUCTION
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3. CARDIOVASCULAR SYSTEM
4. Heart Dilatative cardiomyopathy
Bilateral ventricular enlargement with pleural effusion
Look for pleural effusion and chronic passive congestion in the liver.
5. Heart Hypertrophic cardiomyopathy
Diffuse hypertrophy of the interventricular septum and the left ventricular free wall
May be genetic or secondary to hyperthyroidism
6. Distal aorta Aortic thromboembolism
Focally extensive thomboembolism of the distal aorta with multiple renal infarcts
Much more common in dilatative forms of cardiomyopathy
7. Heart, right ventricle and pulmonary artery
Dirofilaria immitis Focally extensive verminous endarteritis
Microfilaremia is rarely seen and aberrant worm migration is more common.
8. Cerebrum, third ventricle
Dirofilaria immitis Focal filarid parasite in third ventricle
Aberrant migration is more common in aberrant hosts.
9. HEMATOPOIETIC SYSTEM
10. Thymus Malignant lymphoma Thymic Lymphoma, pleural effusion, and pulmonary congestion and edema.
Most common malignancy in the cat. High incidence in association with FeLV infection, especially FeLv‐B. FOCMA antibodies found on membranes of FeLV‐transformed lymphocytes
11. Mesenteric lymph node; intestine
Malignant lymphoma Mesenteric lymph node; intestine: Malignant lymphoma
12. Heart, spinal cord, haired skin,kidney lymphoma
Malignant lymphoma The most common neoplasm in each of these systems with the exception of skin
Lymphoma has a typical creamy white, bulging appearance on cut surface in any organ due to the high number of cells and
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absence of stroma.
13. Liver, spleen Malignant lymphoma Splenic and hepatic lymphoma
May also result in generalized organ enlargement. Need to rule out mast cell tumor in this location as well (less common in liver, though).
14. Thymus Thymoma Thymoma Inset shows thymoma‐associated exfoliative skin disease.
15. Abdominal viscera
Feline infectious peritonitis
Diffuse lymphohistocytic serosal vasculitis and exudative serositis
High protein “honey‐like” exudates in abdominal cavity and fibrin strands.
16. Liver Feline infectious peritonitis
Diffuse severe fibrinous perihepatitis
The end result of abundant fibrin on abdominal organ suggests the existence of severe vasculitis.
17. Abdominal viscera
Feline infectious anemia (Hemobartonella felis)
Generalized icterus with marked splenomegaly
The most common cause of hemolytic anemia in the cat.
18. GASTROINTESTINAL SYSTEM
19. Teeth Osteoclastic resorptive lesion
Osteoclastic resorptive lesion
Partial to full thickess dentinal pitting, often in cheek teeth.
20. Lip, tongue Eosinophilic granuloma
Focally extensive lymphoplasmacytic cheilitis; multifocal eosinophilic and proliferative glossitis
Although a member of the “eosinophilic granuloma complex”, the chronic erosive lesions of the lips (“rodent ulcers”) rarely have any eosinophils left in them.
21. Sublingual gingiva
Focally extensive eosinophilic and granulomatous stomatitis
Not all “rodent ulcers” are ulcerative. Marked cellular infiltrates and granulation tissue may causea lesion which
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appears proliferative.
22. Tongue Feline calicivirus Diffuse vesicular and ulcerative glossitis
Virulent strain of feline calicivirus has necrosis of skin and multiple organ dysfunction
23. Palate Plasma cell stomatitis Bilaterally symmetrical ulcerative and plasmacytic stomatitis
Characteristically located at the glossopalatine arch (faucitis), rule out “kissing ulcers”, an inflammatory response to plaque.
24. Small intestine Feline panleukopenia Diffuse necrohemorrhagic enteritis
Feline parvovirus is the # most common cause of reddened intestines; virus wipes out villar crytps resulting in high mortality.
25. Jejunum String foreign body Linear intestinal ulceration with plication
“Accordion‐pleating” of the intestine is a characteristic finding.
26. Jejunum Taenia taeniaformis, Toxocara cati or Toxascaris leonina
Focally extensive catarrhal and verminous enteritis
27. Jejunum Ancylostoma tubaeformae or braziliense
Multifocal to coalescing ulcerative and hemorrhagic enteritis
Ancylostoma braziliense may cause human infections.
28. Jejunum Histoplasma capsulatum
Diffuse granulomatous enteritis
Rule out diffuse systemic fungal disease, M. avium .
29. Colon Megacolon, Manx spinal cord deformity
Diffuse colonic neuropathy and sacrococcygeal spinal cord dysplasia
Megacolon may be the result of nerve damage, congenital nerve defects or colonic or anal atresia. Inset: Manx spinal cord dysplasia
30. Oral cavity, ventral surface of tongue
Squamous cell carcinoma
Maxillary and lingual squamous cell carcinoma
SCCA is the most common oral malignancy in cats, look under the tongue.
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31. Jejunum Malignant lymphoma Jejunal lymphoma Rule out mast cell tumor. This tumor generally expands the intestinal call and is creamy white on incision.
32. Colon Colonic adenocarcinoma
Colonic adenocarcinoma Epithelial neoplasms are have a “napkin‐ring” effect due to desmoplasia. Proximal bowel will likely be dilated.
33. HEPATOBILIARY AND PANCREATIC SYSTEMS
34. Liver Hepatic lipidosis Diffuse severe hepatic lipidosis
Sequelae are icterus, hepatic failure, and hepatic encephalopathy.
35. Liver Telangiectasia Diffuse hepatic telangiectasia, multifocal nodular exocrine pancreatic hyperplasia
Telangiectasia is an incidental finding in cats and cattle. Pancreatic exocrine hyperplasia is a common aging change
36. Liver Malignant lymphoma Hepatic lymphoma DDx include lymphocytic cholangiohepatitis and granulomatous disease.
37. Liver Biliary cystadenoma Biliary cystadenoma Usually affects one lobe
38. Liver Cholangiocarcinoma Hepatic cholangiocarcinoma Multilobular with umbilicated centers, but difficult to differentiate from other metastatic neoplasms
39. Abdominal cavity
Pancreatic exocrine carcinoma
Pancreatic exocrine carcinoma
Tends to “seed” widely. In the cat, a schirrous response to explanted tumors is known as “carcinomatosis”.
40. Mesenteric fat Necrotizing steatitis Diffuse necrotizing steatitis Yellow‐brown, hard, painful mesenteric and subcutaneous fat due low‐Vit E or hi‐unsaturated fat
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diets.
41. INTEGUMENTARY SYSTEM
42. Haired skin, chin Feline acne Multifocal to coalescing pyogranulomatous folliculitis, furunculosis, and comedone formation
43. Haired skin, face and ear
Notoedres cati Diffuse severe hyperkeratotic facial and auricular dermatitis
Otodectes doesn’t get this bad!
44. Haired skin, face Microsporum canis Multifocal to coalescing hyperkeratotic and proliferative dermatitis
Deep dermatophyte infection will cause draining nodules
45. Haired skin, pinna and head
Sporothrix schenkii Multiofocal to coalescing pyogranulomaout dermatitis and cellulitis
DDx: Cutaneous hi‐mortality calicivirus infection
46. Haired skin, ear Feline calicivirus Focally extensive necrotizing dermatitis
A relatively new form of calicivirus, identified in shelters in California, adds necrotizing cellulitis and a 60% mortality to the many lesions that can be seen with caliciviral infections.
47. Haired skin, face Cryptococcus neoformans
Multifocal to coalescing granulomatous dermatitis
C. grubii and C. gatti can cause infection in immunocompetent hosts.
48. Haired skin Feline ulcerative dermatitis syndrom
Focally extensive traumatic alopecia
Look for linear fibrosis across bottom or biopsy.
49. Haired skin Eosinophilic plaques Multifocal to coalescing eosinophilic and granulomatous dermatitis
No trouble finding eosinophiuls in this lesion!
50. Haired skin Linear granuloma Multifocal to coalescing eosinophilic and granulomatous dermatitis
The back of the hindleg is a very characteristic place for this lesion.
51. Foot pad Plasmacytic Focally extensive May be accompanied by plasmacytic stomatitis.
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pododermatitis plasmacytic pododermatitis 50% of cases are FeLV+
52. Haired skin, nose Mosquito‐bite hypersensitivity
Focally extensive lymphoplasmacytic, eosinophilic, and ulcerative nasal dermatitis
Type 1 hypersensitivity reaction
53. Haired skin, dorsum between shoulder blades
Vaccine‐site fibrosarcoma
Cutaneous fibrosarcoma Very aggressive fibrosarcoma arising at site of previous vaccination
54. Hindlimb, quadriceps muscle
Vaccine‐site fibrosarcoma
Skeletal muscle fibrosarcoma
Microscopic examination may reveal inflammatory foci containing histiocytes with vaccine material.
55. Haired skin Pigmented and cystic basal cell tumor
Cutaneous pigmented and cystic basal cell tumor
This is the most common skin tumor in the cat.
56. Haired skin, preauricular areas
Feline squamous cell carcinoma
Cutaneous squamous cell carcinoma
Commonly seen on face,ears and other thinly haired areas of white cats
57. Haired, skin, planum nasale
Squamous cell carcinoma
Cutaneous squamous cell carcinoma
58. Haired skin Giant cell tumor of soft parts
Giant cell tumor of soft parts Characteristic storiform pattern can be “seen” here grossly. May also arise in tendon sheath or bone.
59. NERVOUS SYSTEM
60. Cerebellum (normal control below)
Feline panleukopenia virus
Diffuse cerebellar hypoplasia Infection in utero damages cells of external granular cell layer
61. Cerebrum, lateral ventricles
Feline infectious peritonitis
Multifocal to coalescing pyogranulomatous ventriculitis with internal hydrocephalus
Granulomatous inflammation obstructing CSF outflow at level of mesencephalic aqueduct
62. Cerebrum, Cryptococcus Multifocal granulomatous encephalitis (actually often
Classic soap‐bubble lesions in the brain of the
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telencephalon neoformans very little inflammation) cat and horse are due to ineffective immune response.
63. Cerebrum Feline ischemic encephalopathy
Unilateral cerebral necrosis and hemorrhage
Characteristically area of middle cerebral artery – associated with Cuterebra larvae (inset), but exact mechanism not elucidated
64. Cerebellum, vermis
Cerebellar coning Cerebellar edema and herniation through foramen magnum
Results of intracranial swelling – may depress the medullary respiratory centers
65. Cerebrum Meningioma Cerebral meningioma Most common brain tumor of cat
66. Cerebrum Astrocytoma Cerebral astrocytoma
67. Eye, iris Iridal lymphoma Iridal lymphoma
68. Eye, iris Diffuse iridal melanoma
Iridal melanoma This lesion progresses over many years, the iris thickens, and may result in secondary glaucoma.
69. Eyes Feline infectious peritonitis
Diffuse fibrinous and suppurative anterior uveitis
Hypopyon – cells and inflammatory material generally settle to the bottom of the eye. Look for vascular lesions in orbital soft tissues outside of the globe.
70. Eyes, iris Acquired portosystemic shunts
Iridal pigmentation The “bronze eyes” of this cat are uniquely associated with PSS in the cat.
71. Middle ear Middle ear polyp Nasopharyngeal polyp Secondary to chronic sinusitis or eustachitis.
72. REPRODUCTIVE SYSTEM
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73. Uterus Uterine Torsion Unilateral uterine torsion and venous infarction
Veins are thin‐walled with lower pressure and infarct well before arteries.
74. Uterus Cystic endometrial hyperplasia
Diffuse cystic endometrial hyperplasia
75. Uterus Pyometra Diffuse suppurative endometritis
Usually follows endometritis or endometrial hyperplasia
76. Uterus Endometrial stromal polyp
Endometrial stromal polyp True uterine tumors very uncommon in the queen. Note the lack of
77. Mammary glands
Mammary hyperplasia Diffuse mammary fibroepithelial hyperplasia
May follow progestogen administration. Non‐ulcerated.
78. RESPIRATORY SYSTEM
79. Nasal septum and turbinates
Feline herpesvirus infection
Diffuse necrosuppurative rhinitis
Usually secondary complication with P. multocida, B. bronchiseptica and M. felis
80. Thoracic cavity Pyothorax Diffuse fibrinosuppurative pleuritis (pyothorax)
Mixed bacterial infections are common with Pasteurella, Bacteoides, and Fusobacterium commonly isolated.
81. Lungs Histoplasma capsulatum
Multifocal to coalescing pyogranulomatous pneumonia
DDx includes other systemic fundal infection and resolving T. gondii infection
82. Lung Toxoplasma gondii Multifocal to coalescing necrotizing and proliferative pneumonia
Yes, cats can be clinically affected. The pneumonia caused by this organism can resemble fungal infections grossly in the florid reparative phase.
83. Lung Paragonimus kellicotti Focally extensive granulomatous pneumonia
Most commonly found in caudal lobes. Fish or
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with intralesional flukes crayfish is intermediate host.
84. Lung Aelurostrongylus abstrusus
Diffuse histiocytic bronchointerstitial and verminous pneumonia
Usually asymptomatic, but severe infections may result in clinical disease in association with bacterial infection.
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86. Lung Feline asthma
Diffuse chronic and mucoid bronchiolitis
Very characteristic collars of inflammatory cells “donuts” around bronchioles. Grossly, lobules associated with affected airways are atelectatic.
87. Lung (cross sections)
88. Thoracic cavity Diaphragmatic hernia Diaphragmatic hernia with pulmonary congestion, edema and pleural effusion
Most commonly resulting from trauma.
89. Thoracic cavity Metastatic mammary neoplasia
Lung, pleural cavity: Mammary adenocarcinoma, metastatic.
Mammary adenocarcinoma has high malignant and metastatic potential in the cat. DDX include malignant lymphoma.
90. URINARY SYSTEM
91. Kidney Polycystic kidney disease
Multiple renal cysts with end‐stage renal disease
Genetic predisposition in Persian cats, may be associated with cysts in biliary and pancreatic ducts
92. Kidneys in situ Chronic interstitial nephritis (end‐stage kidney
Diffuse chronic interstitial nephritis (nephrosclerosis)
Sequela include parathyroid hyperplasia, chronic anemia, osteoporosis
93. Kidney, cortex Renal infarcts Multiple acute and chronic renal infarcts
94. Kidney Pyelonephritis Diffuse suppurative and Radiating hemorrhage and inflammation from the
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hemorrhagic pyelonephritis pelvis
95. Kidney Renal papillary necrosis
Diffuse renal papillary necrosis
Any process that impairs vasa recta circulation will do this; not just NSAIDs
96. Kidney Ethylene glycol toxicosis
Multifocal hemorrhagic necrosis with crystal deposition
Oxalate toxicosis. May also be seen with Vit C overdosage
97. Kidney Amyloidosis Diffuse renal amyloidosis Abyssinian cats are predisposed; lesions mosre severe in medulla. High prevalence in cheetahs.
98. Kidneys Malignant lymphoma Renal lymphoma Main gross differential is feline infectious peritonitis; rule out other metastatic neoplasms
99. Kidney Feline infections peritonitis
Multifocal to coalescing pyogranulomatous renal vasculitis and nephritis
Differentiate from malignant lymphoma grossly based on perivascular location of cellular infiltrate.
100. Urinary bladder Hematuria Hematuria Urinary outflow obstruction is the most common cause (feline urologic syndrome)
101. Urinary bladder Feline urologic syndrome
Cystic struvite urolithiasis with diffuse polypoid cystitis
Chronic bladder infection may be a cause for stone formation
102. ENDOCRINE SYSTEM
103. Thyroid gland Adenomatous thyroid hyperplasia
Bilateral adenomatous thyroid hyperplasia
Most common cause of hyperthyroidism in cats. Thyrotoxicity may result in hypertrophic cardiomyopathy.
104. Parathyroid Parathyroid Diffuse parathyroid May be secondary to diet
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gland hyperplasia hyperplasia or end‐stage renal disease
105. Pituitary gland Pituitary carcinoma Pituitary carcinoma
106. MUSCULOSKELETAL SYSTEM
107. Rib cage Osteogenesis imperfecta
Multiple rib fractures Defect in collagen type 1 production, with concomitant osteopenia. Look for joint, tooth, sclera abnormalities.
108. Hindlimbs Femoral and tibial fractures with callus
109. Radius, ulna Porphyria Long bone porphyria Congenital defect of uroporphyrinogen‐3‐cosynthetase. Concomitant anemia
110. Cervical and thoracic vertebrae
Vit A toxicity Vertebral bodies, cervical and thoracic: Severe diffuse hyperostosis and spodylosis
Vitamin A is stimulatory to osteoblast in adult animals, but inhibitory in young animals
111. Skull and frontal bone
Feline alpha mannosidosis
Facial dysmorphism with frontal done dysplasia
The “bossing” of the forehead isseen in association with other defects in the flat bones in kittens with a number of storage diseases.
112. Skull, scapular neck
Multiple cartilaginous exostoses
Cranial and scapular osteochondromas
113. Femoral head Malignant lymphoma Femoral malignant lymphoma
Bone is not an uncommon site for lymphoma in cats
114. Distal femur Osteosarcoma Femoral osteosarcoma Can occur in any species. When compared to lymphoma, is not as dense.
