BCSE - Basic and Clinical Sciences Examination Anatomic and Clinical Pathology Questions and Answers — Questions and Answers
Question 1: A 6-year-old Golden Retriever is presented with lethargy, polyuria, and polydipsia. A complete blood count (CBC) and serum chemistry panel are performed. The CBC is unremarkable. The chemistry panel reveals a blood glucose of 450 mg/dL (normal: 75-120 mg/dL) and elevated liver enzymes. A urinalysis shows 4+ glucosuria and 2+ ketonuria. Which of the following is the most likely pathologic process responsible for these findings?
- Immune-mediated destruction of pancreatic beta cells (Correct answer)
- Neoplastic proliferation of adrenal cortical cells
- Renal tubular insensitivity to antidiuretic hormone
- Glycogen storage disease in hepatocytes
Correct answer: Immune-mediated destruction of pancreatic beta cells
The clinical signs (polyuria, polydipsia) combined with severe hyperglycemia, glucosuria, and ketonuria are classic for diabetes mellitus. In dogs, the most common cause of diabetes mellitus is the immune-mediated destruction of insulin-producing beta cells in the pancreatic islets, leading to absolute insulin deficiency.
Question 2: A biopsy from a skin mass on an 8-year-old Boxer is submitted for histopathology. The pathologist describes 'sheets of round cells with distinct cell borders, abundant eosinophilic granular cytoplasm, and central, round nuclei.' There is minimal pleomorphism and a low mitotic rate. Mast cell granules are not observed with routine H&E staining but would likely be prominent with which special stain?
- Prussian Blue
- Toluidine Blue (Correct answer)
- Periodic acid-Schiff (PAS)
- Masson's Trichrome
Correct answer: Toluidine Blue
The description is highly suggestive of a mast cell tumor, which is common in dogs, particularly Boxer breeds. The characteristic cytoplasmic granules of mast cells are metachromatic, meaning they stain a different color than the dye itself. Toluidine blue is a classic metachromatic stain used to highlight mast cell granules, which will stain purple against a blue background.
Question 3: Which of the following sets of clinical pathology findings is most consistent with a diagnosis of disseminated intravascular coagulation (DIC)?
- Increased platelet count, prolonged PT, prolonged aPTT, decreased FDPs
- Thrombocytopenia, prolonged PT, prolonged aPTT, elevated FDPs (Correct answer)
- Thrombocytopenia, shortened PT, shortened aPTT, normal FDPs
- Normal platelet count, normal PT, normal aPTT, elevated FDPs
Correct answer: Thrombocytopenia, prolonged PT, prolonged aPTT, elevated FDPs
Disseminated intravascular coagulation (DIC) is a complex syndrome of systemic, uncontrolled activation of coagulation. This leads to widespread microthrombi formation, consuming platelets and coagulation factors, which results in thrombocytopenia and prolongation of clotting times (PT and aPTT). Simultaneously, the fibrinolytic system is activated to break down clots, leading to an increase in fibrin degradation products (FDPs).
Question 4: A dairy cow dies after a short period of ataxia, bellowing, and convulsions. At necropsy, the brain appears grossly normal. However, histopathology of the cerebral cortex reveals laminar cortical necrosis, characterized by a layer of dead, eosinophilic neurons. This finding is most pathognomonic for which condition?
- Listeriosis
- Rabies
- Bovine Spongiform Encephalopathy
- Polioencephalomalacia (Correct answer)
Correct answer: Polioencephalomalacia
Laminar cortical necrosis is the classic histologic lesion of polioencephalomalacia (PEM) in ruminants. This condition is most often associated with thiamine (Vitamin B1) deficiency or high sulfur intake, which disrupts glucose metabolism in the brain and leads to the death of neurons in the cerebral cortex.
Question 5: A laboratory is performing a crossmatch for a feline blood transfusion. The donor is blood type A and the recipient is blood type B. What is the most likely outcome if this transfusion proceeds without a crossmatch?
- A mild, delayed hemolytic reaction due to low-titer isoantibodies.
- A severe, acute hemolytic transfusion reaction. (Correct answer)
- No reaction, as type A is a universal donor in cats.
- Graft-versus-host disease.
Correct answer: A severe, acute hemolytic transfusion reaction.
Cats have naturally occurring, high-titer alloantibodies against the blood type they lack. Type B cats have very strong anti-A antibodies. Transfusing type A blood into a type B cat will result in a severe, acute, and potentially fatal hemolytic transfusion reaction due to the recipient's potent anti-A antibodies causing massive destruction of the transfused red blood cells.
Question 6: A routine urinalysis is performed on a dog with a suspected urinary tract infection. The microscopic examination of the urine sediment reveals numerous rod-shaped bacteria, more than 10 white blood cells per high-power field, and many struvite crystals. Which of the following is a common consequence of this type of infection?
- The urine pH will become more acidic.
- The urine specific gravity will be fixed at 1.010.
- The urine pH will become more alkaline. (Correct answer)
- The formation of calcium oxalate crystals will be promoted.
Correct answer: The urine pH will become more alkaline.
Struvite (magnesium ammonium phosphate) crystals tend to form in alkaline urine. Many common urinary tract infections in dogs are caused by urease-producing bacteria (e.g., Staphylococcus, Proteus). These bacteria break down urea into ammonia, which raises the urine pH (makes it more alkaline), promoting the precipitation of struvite crystals and potentially leading to stone formation.
BCSE - Basic and Clinical Sciences Examination Anatomic and Clinical Pathology Questions and Answers
A 6-year-old Golden Retriever is presented with lethargy, polyuria, and polydipsia.
A complete blood count (CBC) and serum chemistry panel are performed.
The CBC is unremarkable.
The chemistry panel reveals a blood glucose of 450 mg/dL (normal: 75-120 mg/dL) and elevated liver enzymes.
A urinalysis shows 4+ glucosuria and 2+ ketonuria.
Which of the following is the most likely pathologic process responsible for these findings?