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ACVP Veterinary Pathology study materials
ACVP Veterinary Pathology study resources

ACVP Veterinary Pathology practice questions

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Question 1Veterinary Anatomic Pathology

Which microscopic feature best distinguishes a malignant neoplasm from a benign one in a tissue biopsy?

  1. Uniform cells with abundant eosinophilic cytoplasm
  2. High mitotic rate with atypical mitoses and invasion Correct answer.
  3. Well-circumscribed borders with a fibrous capsule
  4. Slow growth over several months with no recurrence

Explanation

Malignancy is defined by invasive behavior and cytologic atypia, of which atypical mitoses and tissue invasion are hallmarks. Benign tumors tend to be well demarcated, slow growing, and composed of uniform cells.

Question 2Veterinary Anatomic Pathology

A dog has a markedly prolonged activated partial thromboplastin time with normal prothrombin time and normal platelet count. Which factor deficiency is most consistent with this pattern?

  1. Factor X deficiency
  2. Factor I (fibrinogen) deficiency
  3. Factor VIII deficiency Correct answer.
  4. Factor VII deficiency

Explanation

The aPTT measures the intrinsic and common pathways, so an isolated aPTT prolongation points to an intrinsic pathway factor such as VIII, IX, XI, or XII. PT measures the extrinsic and common pathways and would be prolonged with factor VII or common pathway defects.

Question 3Veterinary Anatomic Pathology

In a tissue section, which stain is most appropriate to highlight collagen fibers for assessing fibrosis?

  1. Prussian blue
  2. Perl's iron
  3. Congo red
  4. Masson trichrome Correct answer.

Explanation

Masson trichrome stains collagen blue or green against red-stained cytoplasm, making it ideal for evaluating fibrosis. Prussian blue and Perl's stain iron, and Congo red highlights amyloid.

Question 4Veterinary Anatomic Pathology

A biopsy of a canine skin mass shows sheets of round cells with abundant pale cytoplasm and a 'storiform' to whorled pattern, with no significant atypia. Which diagnosis is most likely?

  1. Histiocytoma Correct answer.
  2. Hemangiosarcoma
  3. Squamous cell carcinoma
  4. Mast cell tumor

Explanation

Histiocytomas are composed of uniform round to polygonal histiocytes often arranged in sheets with a whorled pattern and minimal atypia. The other listed tumors have distinct cytologic or architectural features (granules, vascular channels, squamous differentiation).

Question 5Veterinary Anatomic Pathology

Which organ is the primary site of hematopoiesis in the late-gestation fetus and neonate of most domestic species?

  1. Spleen
  2. Liver Correct answer.
  3. Bone marrow
  4. Thymus

Explanation

Hematopoiesis shifts from the yolk sac to the liver during fetal life, and the liver remains the dominant site in the late fetus and neonate before marrow takes over. The spleen and marrow contribute later, and the thymus is a site of T-cell maturation.

Question 6Veterinary Anatomic Pathology

A liver from a dog with chronic right-sided heart failure shows centrilobular congestion and necrosis. Which vascular mechanism best explains this distribution?

  1. Hepatic artery thrombosis
  2. Portal vein obstruction
  3. Biliary duct obstruction
  4. Increased hepatic venous pressure Correct answer.

Explanation

Right-sided heart failure raises central venous and hepatic venous pressure, causing centrilobular congestion and hypoxic necrosis because the centrilobular zone is farthest from the arterial supply. Portal or biliary obstruction produces different patterns, and arterial thrombosis is not the primary mechanism.

Question 7Veterinary Anatomic Pathology

Which lesion is the classic gross finding of feline infectious peritonitis in the effusive form?

  1. Caseous lymphadenitis of the mesenteric nodes
  2. Fibrinous to granulomatous inflammation on serosal surfaces Correct answer.
  3. Suppurative bronchopneumonia
  4. Segmental hemorrhagic enteritis

Explanation

FIP produces a pyogranulomatous vasculitis with fibrin-rich exudate on serosal surfaces, leading to effusion. The other patterns are not characteristic of FIP.

Question 8Veterinary Anatomic Pathology

A tissue section shows amorphous, eosinophilic, extracellular material that stains apple-green under polarized light after Congo red staining. What is the material?

  1. Fibrin
  2. Collagen
  3. Amyloid Correct answer.
  4. Hemosiderin

Explanation

Amyloid is an amorphous eosinophilic proteinaceous deposit that exhibits apple-green birefringence under polarized light with Congo red. Fibrin, collagen, and hemosiderin do not show this property.

Question 9Veterinary Anatomic Pathology

A renal biopsy shows diffuse thickening of glomerular capillary basement membranes without significant cellular proliferation. Which mechanism best explains this change?

  1. Proliferative glomerulonephritis from mesangial cell hyperplasia
  2. Pyelonephritis from ascending bacterial infection
  3. Membranous glomerulonephritis from immune complex deposition Correct answer.
  4. Renal dysplasia from abnormal differentiation

Explanation

Membranous glomerulonephritis is characterized by immune complex deposition along the basement membrane causing diffuse thickening without marked hypercellularity. Proliferative forms show increased cellularity, and the other options describe different processes.

Question 10Veterinary Anatomic Pathology

Which cell type is the principal source of collagen in a healing wound?

  1. Neutrophil
  2. Endothelial cell
  3. Macrophage
  4. Fibroblast Correct answer.

Explanation

Fibroblasts synthesize collagen and other extracellular matrix components during wound repair. Neutrophils and macrophages participate in inflammation and debridement, and endothelial cells form new vessels.

Question 11Veterinary Anatomic Pathology

A dog with a splenic mass has a biopsy showing irregular blood-filled channels lined by pleomorphic endothelial cells. Which tumor is most likely?

  1. Splenic fibrosarcoma
  2. Splenic hemangiosarcoma Correct answer.
  3. Splenic hemangioma
  4. Splenic lymphoma

Explanation

Hemangiosarcoma is a malignant vascular tumor forming irregular channels lined by atypical endothelial cells, commonly arising in the spleen. Hemangioma is benign and well differentiated, while fibrosarcoma and lymphoma are not vascular.

Question 12Veterinary Anatomic Pathology

Which finding is most characteristic of acute inflammation in a tissue section?

  1. Eosinophilic infiltration with mast cells
  2. Granuloma formation with giant cells
  3. Neutrophilic infiltration with edema Correct answer.
  4. Lymphoplasmacytic infiltration with fibrosis

Explanation

Acute inflammation is dominated by neutrophils and edema. Lymphoplasmacytic infiltrates with fibrosis indicate chronicity, granulomas indicate a chronic granulomatous process, and eosinophils suggest allergic or parasitic responses.

Question 13Veterinary Anatomic Pathology

A cow has a liver fluke infestation with thickened bile ducts and periductal fibrosis. Which fluke is most likely responsible?

  1. Fasciola hepatica Correct answer.
  2. Dictyocaulus viviparus
  3. Ostertagia ostertagi
  4. Trichostrongylus axei

Explanation

Fasciola hepatica migrates through the liver and bile ducts, causing cholangitis and periductal fibrosis. The other organisms are lung or abomasal parasites.

Question 14Veterinary Anatomic Pathology

A tissue section shows cells with abundant brown granular pigment that stains blue with Prussian blue. What is the pigment?

  1. Bilirubin
  2. Hemosiderin Correct answer.
  3. Melanin
  4. Lipofuscin

Explanation

Hemosiderin is an iron-containing pigment that stains blue with Prussian blue. Melanin is brown but does not stain for iron, lipofuscin is a wear-and-tear pigment, and bilirubin is a bile pigment.

Question 15Veterinary Anatomic Pathology

A dog develops a necropsy finding of a large, pale, firm mass in the right atrium. Which tumor is most likely?

  1. Hemangiosarcoma Correct answer.
  2. Pulmonary carcinoma
  3. Aortic body tumor
  4. Right atrial myxoma

Explanation

Hemangiosarcoma commonly arises in the right atrium and auricle of dogs, appearing as a dark red to pale, firm mass. Aortic body tumors arise at the heart base, myxomas are uncommon, and pulmonary carcinoma is a lung tumor.

Question 16Veterinary Anatomic Pathology

Which type of necrosis is most characteristic of an infarct in the brain?

  1. Caseous necrosis
  2. Fat necrosis
  3. Coagulative necrosis
  4. Liquefactive necrosis Correct answer.

Explanation

Ischemic injury in the central nervous system leads to liquefactive necrosis because of the high lipid content and lack of a supporting stromal framework. Coagulative necrosis occurs in most other solid organs, caseous necrosis in tuberculosis, and fat necrosis in pancreatic or adipose injury.

Question 17Veterinary Anatomic Pathology

A horse with chronic weight loss has a large, firm mass in the cecum. Histology shows spindle cells forming streams with collagen production and mild atypia. Which diagnosis is most likely?

  1. Adenocarcinoma
  2. Melanoma
  3. Gastrointestinal stromal tumor Correct answer.
  4. Lymphoma

Explanation

Gastrointestinal stromal tumors are spindle cell neoplasms of the intestinal wall that produce collagen and show mild to moderate atypia. Lymphoma is round cell, adenocarcinoma is epithelial and glandular, and melanoma contains pigment.

Question 18Veterinary Anatomic Pathology

Which process best describes the formation of a thrombus in a vessel with endothelial injury?

  1. Platelet adhesion and aggregation followed by fibrin formation Correct answer.
  2. Vasodilation with increased vascular permeability
  3. Lymphatic obstruction with protein-rich effusion
  4. Diapedesis of erythrocytes through intact endothelium

Explanation

Thrombosis follows Virchow's triad, and endothelial injury triggers platelet adhesion and aggregation with subsequent fibrin deposition. Diapedesis, effusion, and vasodilation describe hemorrhage, edema, and inflammation rather than thrombosis.

Question 19Veterinary Anatomic Pathology

A tissue section of a canine lymph node shows loss of architecture with sheets of large atypical lymphoid cells. Which diagnosis is most likely?

  1. Lymphoma Correct answer.
  2. Histiocytic sarcoma
  3. Plasmacytoma
  4. Reactive lymphoid hyperplasia

Explanation

Effacement of nodal architecture by sheets of atypical lymphoid cells indicates lymphoma. Reactive hyperplasia preserves architecture with follicular or paracortical expansion, and histiocytic sarcoma and plasmacytoma have different cytologic features.

Question 20Veterinary Anatomic Pathology

Which of the following best defines metaplasia?

  1. Increase in cell number within a tissue
  2. Programmed cell death with cell shrinkage
  3. Reversible replacement of one mature cell type by another Correct answer.
  4. Irreversible loss of tissue architecture with scarring

Explanation

Metaplasia is a reversible change in which one mature differentiated cell type is replaced by another, often in response to chronic irritation. The other options describe fibrosis, hyperplasia, and apoptosis.

Question 21Veterinary Anatomic Pathology

A dog with a portosystemic shunt develops hepatic encephalopathy. Which histologic change in the liver is most expected?

  1. Massive centrilobular necrosis
  2. Biliary hyperplasia with portal fibrosis
  3. Hepatic atrophy with small hepatocytes Correct answer.
  4. Hepatocellular swelling with glycogen accumulation

Explanation

Portosystemic shunts reduce hepatic blood flow and trophic factors, leading to hepatocellular atrophy and small hepatocytes. Swelling, massive necrosis, and biliary fibrosis are not the primary changes.

Question 22Veterinary Anatomic Pathology

Which infectious agent is classically associated with caseous necrosis and granuloma formation in the lungs of cattle?

  1. Mycobacterium bovis Correct answer.
  2. Bovine viral diarrhea virus
  3. Pasteurella multocida
  4. Mannheimia haemolytica

Explanation

Mycobacterium bovis causes granulomatous inflammation with caseous necrosis in cattle. The other agents cause suppurative pneumonia or viral disease without caseous granulomas.

Question 23Veterinary Anatomic Pathology

A skin biopsy from a cat shows numerous eosinophils, mast cells, and collagen degeneration. Which condition is most consistent with this pattern?

  1. Eosinophilic granuloma complex Correct answer.
  2. Squamous cell carcinoma
  3. Malignant melanoma
  4. Demodicosis

Explanation

Eosinophilic granuloma complex features eosinophils, mast cells, and flame figures with collagen degeneration. The other conditions have distinct neoplastic or parasitic features.

Question 24Veterinary Anatomic Pathology

Which finding on histology best indicates that a lesion is a granuloma?

  1. Sheets of atypical lymphocytes
  2. Aggregates of macrophages with multinucleated giant cells Correct answer.
  3. Cords of collagen with scattered fibroblasts
  4. Diffuse infiltration of neutrophils with edema

Explanation

Granulomas are organized collections of activated macrophages, often with multinucleated giant cells, formed in response to persistent antigens. Neutrophils indicate suppuration, lymphocytes indicate lymphoid infiltrates, and collagen with fibroblasts indicates fibrosis.

Question 25Veterinary Anatomic Pathology

A renal tumor in a dog is composed of cells with abundant clear cytoplasm and is diagnosed as clear cell carcinoma. Which intracellular change most likely accounts for the clear appearance?

  1. Melanin accumulation
  2. Calcification
  3. Lipid accumulation Correct answer.
  4. Iron deposition

Explanation

Clear cell tumors typically contain abundant intracellular lipid that dissolves during processing, leaving empty vacuoles. Iron, melanin, and calcium produce pigmented or basophilic deposits rather than clear cytoplasm.

Question 26Veterinary Anatomic Pathology

Which form of cell death is best described as programmed, caspase-dependent, and typically affects single scattered cells without inciting significant inflammation?

  1. Liquefactive necrosis
  2. Caseous necrosis
  3. Apoptosis Correct answer.
  4. Coagulative necrosis

Explanation

Apoptosis is an energy-dependent, caspase-mediated process that removes individual cells and leaves minimal inflammation because cellular contents are packaged into membrane-bound bodies. Necrosis in its various forms is generally accompanied by inflammation.

Question 27Veterinary Anatomic Pathology

A section of skeletal muscle shows loss of cross-striations, hyalinized hypereosinophilic fibers, and focal mineralization. Which term best describes this change?

  1. Dysplasia
  2. Atrophy
  3. Hydropic degeneration
  4. Zenker's necrosis Correct answer.

Explanation

Zenker's degeneration/necrosis is the classic hyaline eosinophilic necrosis of skeletal muscle fibers, often with loss of striations and subsequent mineralization. Atrophy reduces fiber size without this hyaline change.

Question 28Veterinary Anatomic Pathology

Which pathologic process is characterized by increased numbers of cells in a tissue due to an increased rate of cell division?

  1. Metaplasia
  2. Hypertrophy
  3. Atrophy
  4. Hyperplasia Correct answer.

Explanation

Hyperplasia is an increase in cell number through proliferation and occurs only in tissues capable of mitotic division. Hypertrophy increases cell size rather than number.

Question 29Veterinary Anatomic Pathology

A biopsy of a chronically sun-exposed feline ear margin shows thickened, hyperkeratotic epidermis with disorganized maturation and marked nuclear atypia confined above the basement membrane. What is the most appropriate diagnosis?

  1. Basal cell tumor
  2. Actinic keratosis (carcinoma in situ) Correct answer.
  3. Sebaceous adenoma
  4. Squamous cell carcinoma, invasive

Explanation

Atypia and disordered maturation confined by an intact basement membrane define carcinoma in situ, commonly actinic keratosis in sun-damaged skin. Invasion through the basement membrane would be required for invasive carcinoma.

Question 30Veterinary Anatomic Pathology

Which feature most reliably distinguishes a benign neoplasm from a malignant one on histology?

  1. Cellular pleomorphism
  2. High mitotic rate
  3. Presence of a capsule
  4. Metastasis to a distant site Correct answer.

Explanation

Metastasis is the definitive criterion of malignancy because it demonstrates the capacity to invade and colonize distant tissues. Mitotic rate, pleomorphism, and encapsulation are supportive features but can occur in benign or low-grade lesions.

Question 31Veterinary Anatomic Pathology

A tissue section contains numerous multinucleated giant cells with nuclei arranged in a peripheral horseshoe pattern around a central space. What is this structure called?

  1. Touton giant cell
  2. Foreign body giant cell
  3. Langhans giant cell Correct answer.
  4. Reed-Sternberg cell

Explanation

Langhans giant cells have nuclei arranged in a peripheral arc or horseshoe and are typical of granulomatous inflammation, especially tuberculosis. Foreign body giant cells have haphazardly arranged nuclei.

Question 32Veterinary Anatomic Pathology

Which morphologic change is the hallmark of reversible acute cell injury prior to the point of no return?

  1. Plasma membrane rupture
  2. Cellular swelling Correct answer.
  3. Nuclear fragmentation
  4. Calcification of mitochondria

Explanation

Cellular swelling from failure of the ATP-dependent sodium-potassium pump is the earliest and most consistent sign of reversible injury. Nuclear fragmentation and membrane rupture indicate irreversible injury.

Question 33Veterinary Anatomic Pathology

In a section of kidney, a focus of coagulative necrosis is bordered by a zone of neutrophils and hyperemic vessels. Which pathologic process does this pattern represent?

  1. Amyloid deposition
  2. Granulomatous inflammation
  3. Acute infarction with inflammation Correct answer.
  4. Fatty change

Explanation

Coagulative necrosis with a surrounding inflammatory and hyperemic rim is the typical appearance of an infarct in solid organs such as kidney. Granulomatous inflammation would show macrophages and giant cells.

Question 34Veterinary Anatomic Pathology

Which tissue change is most consistent with chronic passive congestion of the liver?

  1. Periportal fibrosis with bile duct proliferation
  2. Massive hepatic necrosis with hemorrhage
  3. Centrilobular hepatocyte atrophy with hemosiderin-laden macrophages Correct answer.
  4. Diffuse hepatocellular swelling with lipid vacuoles

Explanation

Chronic passive congestion causes centrilobular hypoxia, hepatocyte loss or atrophy, and accumulation of hemosiderin in macrophages (cardiac cirrhosis pattern). Bile duct proliferation and periportal fibrosis suggest biliary disease.

Question 35Veterinary Anatomic Pathology

A section of lung shows alveoli filled with pink, homogeneous, finely granular material and few cells, consistent with edema fluid. Which additional finding would best support acute lung injury rather than simple hydrostatic edema?

  1. Increased alveolar macrophages with hemosiderin
  2. Bronchial cartilage hyperplasia
  3. Thickened alveolar septa with fibrosis
  4. Hyaline membranes lining alveolar walls Correct answer.

Explanation

Hyaline membranes lining alveoli represent fibrin and necrotic debris typical of acute alveolar damage, distinguishing it from pure hydrostatic edema. Hemosiderin-laden macrophages indicate chronic hemorrhage.

Question 36Veterinary Anatomic Pathology

Which cell is the principal effector of immediate-type hypersensitivity reactions in the lung and skin of domestic animals?

  1. Neutrophil
  2. Fibroblast
  3. Mast cell Correct answer.
  4. Plasma cell

Explanation

Mast cells release histamine and other mediators after IgE cross-linking, driving immediate hypersensitivity. Plasma cells produce antibody but do not mediate the acute response.

Question 37Veterinary Anatomic Pathology

A dog's lymph node shows marked follicular hyperplasia with prominent germinal centers. What does this change most likely indicate?

  1. Granulomatous lymphadenitis
  2. Lymphoma with neoplastic follicles
  3. Metastatic carcinoma
  4. Antigenic stimulation with B-cell proliferation Correct answer.

Explanation

Follicular hyperplasia with active germinal centers reflects antigen-driven B-cell proliferation and is a reactive change. Neoplastic follicles in lymphoma typically lack normal germinal center polarization and mantle zones.

Question 38Veterinary Anatomic Pathology

Which histologic finding best indicates that a neoplasm has arisen from glandular epithelium?

  1. Keratin pearls within cell nests
  2. Spindle cells in interlacing bundles
  3. Formation of acini or tubules by neoplastic cells Correct answer.
  4. Cartilage matrix production

Explanation

Glandular differentiation is recognized by formation of acini, tubules, or mucin production by neoplastic epithelial cells. Keratin pearls indicate squamous differentiation.

Question 39Veterinary Anatomic Pathology

A skin mass in an older dog consists of spindle cells arranged in whorls with collagen bundles, and special stains show individual cells wrapping around collagen. What is the most likely diagnosis?

  1. Mast cell tumor
  2. Melanoma
  3. Perivascular wall tumor (perivascular wall tumor) Correct answer.
  4. Squamous cell carcinoma

Explanation

Whorled spindle cells wrapping collagen bundles are characteristic of perivascular wall tumors, which show perivascular differentiation. Mast cell tumors are composed of round cells with metachromatic granules.

Question 40Veterinary Anatomic Pathology

Which change in a blood vessel wall is the earliest event in the pathogenesis of atherosclerosis in animals?

  1. Thrombosis of the lumen
  2. Aneurysmal dilation
  3. Calcification of the tunica media
  4. Endothelial injury with monocyte adhesion Correct answer.

Explanation

Endothelial injury initiates atherosclerosis by allowing monocyte adhesion and migration into the intima, where they become macrophages and form foam cells. Medial calcification and thrombosis occur later or represent separate processes.

Question 41Veterinary Anatomic Pathology

A tissue section of a healing wound shows numerous small blood vessels, fibroblasts, and loose extracellular matrix. What term best describes this tissue?

  1. Caseous exudate
  2. Fibrinous exudate
  3. Granulation tissue Correct answer.
  4. Fibrous scar

Explanation

Granulation tissue is the vascular, fibroblast-rich tissue that fills wounds during repair and is later replaced by a collagenous scar. Fibrous scar is the mature end stage with dense collagen and few vessels.

Question 42Veterinary Anatomic Pathology

A horse has a large, firm, pale mass at the base of the heart. Histology shows spindle cells with collagen deposition. Which tumor is most likely?

  1. Hemangiosarcoma
  2. Myxoma
  3. Lymphoma
  4. Fibroma Correct answer.

Explanation

A firm, pale, collagenous spindle-cell tumor is consistent with fibroma or fibrosarcoma. Hemangiosarcoma would show blood-filled vascular channels, and lymphoma would show sheets of round lymphoid cells.

Question 43Veterinary Anatomic Pathology

A section of liver shows irregular, pale, eosinophilic areas of hepatocyte loss with a surrounding zone of hemorrhage and no significant fibrosis. What is the most likely cause?

  1. Amyloidosis
  2. Acute toxic or ischemic hepatocellular necrosis Correct answer.
  3. Hepatic lipidosis
  4. Chronic biliary obstruction

Explanation

Acute hepatocellular necrosis presents as pale eosinophilic areas of cell loss with hemorrhage and minimal fibrosis. Chronic biliary obstruction and amyloidosis produce different patterns.

Question 44Veterinary Anatomic Pathology

Which histologic feature is most characteristic of a benign epithelial tumor of the skin?

  1. Lymphatic invasion by tumor cells
  2. Infiltrative growth into the dermis
  3. Well-demarcated proliferation with uniform cells and intact basement membrane Correct answer.
  4. Marked nuclear pleomorphism and atypical mitoses

Explanation

Benign epithelial tumors are well demarcated, composed of uniform cells, and remain confined by the basement membrane. Infiltration, pleomorphism, and lymphatic invasion indicate malignancy.

Question 45Veterinary Anatomic Pathology

A brain section shows a focus of malacia with gitter cells and a surrounding zone of edema. What process does this represent?

  1. Coagulative necrosis
  2. Fibrinoid necrosis
  3. Liquefactive necrosis Correct answer.
  4. Caseous necrosis

Explanation

The central nervous system undergoes liquefactive necrosis after infarction, with phagocytic gitter cells clearing debris and surrounding edema. Coagulative necrosis predominates in most other solid organs.

Question 46Veterinary Anatomic Pathology

A biopsy of a canine prostate shows a proliferation of small glands lined by two cell layers with uniform nuclei and no invasion. What is the most likely diagnosis?

  1. Prostatic adenocarcinoma
  2. Prostatitis
  3. Benign prostatic hyperplasia Correct answer.
  4. Transitional cell carcinoma

Explanation

Benign prostatic hyperplasia features glandular proliferation with retained two-cell-layer architecture and uniform nuclei. Adenocarcinoma shows a single layer of atypical cells with invasion.

Question 47Veterinary Anatomic Pathology

Which finding in a tissue section indicates dystrophic calcification?

  1. Golden-brown pigment staining with Prussian blue
  2. Eosinophilic amorphous deposits staining with Congo red
  3. Basophilic deposits in normal tissue with hypercalcemia
  4. Basophilic granular deposits in necrotic tissue with normal serum calcium Correct answer.

Explanation

Dystrophic calcification occurs in dead or damaged tissue despite normal serum calcium. Metastatic calcification occurs in normal tissue with hypercalcemia.

Question 48Veterinary Anatomic Pathology

A section of a canine spleen shows a well-demarcated red nodule composed of haphazardly arranged blood-filled spaces separated by fibrous trabeculae. What is the most likely diagnosis?

  1. Splenic histiocytic sarcoma
  2. Splenic hemangioma Correct answer.
  3. Splenic mast cell tumor
  4. Splenic lymphoma

Explanation

A well-demarcated proliferation of blood-filled vascular spaces with fibrous trabeculae is characteristic of hemangioma. Lymphoma and histiocytic sarcoma are composed of round cells rather than vascular channels.

Question 49Veterinary Anatomic Pathology

Which change in the intestinal mucosa is most consistent with chronic enteritis?

  1. Villous blunting with increased intraepithelial lymphocytes Correct answer.
  2. Submucosal edema with dilated lymphatics
  3. Fibrinoid necrosis of crypt epithelium
  4. Transmural neutrophilic infiltration with necrosis

Explanation

Chronic enteritis is characterized by villous blunting, crypt hyperplasia, and increased intraepithelial lymphocytes. Transmural neutrophilic necrosis indicates acute severe or ulcerative disease.

Question 50Veterinary Anatomic Pathology

A section of skin shows a subepidermal blister with acantholytic keratinocytes and eosinophils. Which condition is most consistent with this finding?

  1. Demodicosis
  2. Superficial bacterial pyoderma
  3. Feline eosinophilic granuloma
  4. Pemphigus foliaceus Correct answer.

Explanation

Pemphigus foliaceus is an autoimmune pustular dermatosis with subcorneal or subepidermal acantholysis and eosinophils. Demodicosis and pyoderma are infectious and do not show primary acantholysis.