AP/CP Pathology Board Certification Exam 2026: Comprehensive
ABPath Practice Test — General Pathology, Systemic Pathology,
Hematopathology, Transfusion Medicine, Microbiology, Chemical
Pathology & Laboratory Management — 190 Multiple-Choice
Questions with Answers & Detailed Rationales
Question 1
A 58-year-old man with a 30-pack-year smoking history presents with haemoptysis and a 4
cm hilar mass. Biopsy reveals sheets of small blue round cells with nuclear moulding, scant
cytoplasm, and frequent mitotic figures. Immunohistochemistry shows positivity for CD56,
synaptophysin, and chromogranin. Which of the following is the most likely diagnosis?
A. Squamous cell carcinoma
B. Small cell carcinoma
C. Adenocarcinoma
D. Large cell neuroendocrine carcinoma
Correct Answer: B
Explanation: Small cell carcinoma is a high-grade neuroendocrine tumor with small blue
cells, nuclear molding, and neuroendocrine marker positivity. It is strongly associated with
smoking.
Question 2
A 42-year-old woman undergoes excisional biopsy of a 2.5 cm breast mass. Microscopy
shows invasive ductal carcinoma with tubule formation in >75% of the tumor, mild nuclear
,pleomorphism, and a mitotic count of 5 mitoses per 10 high-power fields. According to the
Nottingham grading system, what is the histologic grade?
A. Grade I
B. Grade II
C. Grade III
D. Grade IV
Correct Answer: A
Explanation: Tubule formation >75% (score 1), mild pleomorphism (score 1), and mitotic
count ≤7/10 HPF (score 1) yields a total score of 3, corresponding to Grade I.
Question 3
A 67-year-old man with chronic atrial fibrillation presents with acute abdominal pain and
bloody diarrhea. Colonoscopy reveals a segment of dusky, edematous mucosa in the
descending colon. Biopsy shows coagulative necrosis of the mucosa and submucosa with
preserved crypt architecture. Which of the following best describes this pathologic process?
A. Liquefactive necrosis
B. Ischemic bowel infarction
C. Ulcerative colitis
D. Pseudomembranous colitis
Correct Answer: B
Explanation: Ischemic bowel injury produces coagulative necrosis in the early phase, with
preserved tissue architecture, reflecting the ischemic insult from embolic occlusion in atrial
fibrillation.
,Question 4
A 34-year-old woman presents with fatigue, jaundice, and splenomegaly. Laboratory studies
show hemoglobin 8.2 g/dL, reticulocyte count 12%, indirect bilirubin 3.8 mg/dL, and LDH
520 U/L. Direct antiglobulin test (DAT) is positive for IgG and complement. Which of the
following is the most likely diagnosis?
A. Hereditary spherocytosis
B. Warm autoimmune hemolytic anemia
C. Cold agglutinin disease
D. Paroxysmal nocturnal hemoglobinuria
Correct Answer: B
Explanation: Warm AIHA presents with anemia, reticulocytosis, indirect hyperbilirubinemia,
elevated LDH, and a DAT positive for IgG (often with complement), reflecting extravascular
hemolysis.
Question 5
A 55-year-old man with a history of myocardial infarction undergoes autopsy. Gross
examination of the heart reveals a 3 cm area of thinning and fibrosis in the anterior left
ventricular wall. Microscopy shows replacement of myocardium by dense collagen with
scattered viable myocytes at the periphery. Which of the following best describes this
finding?
A. Acute myocardial infarction
B. Remote myocardial infarction
C. Hypertrophic cardiomyopathy
D. Myocarditis
, Correct Answer: B
Explanation: Remote myocardial infarction is characterized by replacement fibrosis with
thinning of the ventricular wall, occurring weeks to months after the ischemic event.
Question 6
A 28-year-old woman presents with recurrent episodes of swelling of the lips, tongue, and
extremities without urticaria. Symptoms began in adolescence. Laboratory studies show low
C4 and low C1 inhibitor levels. Which of the following is the most likely diagnosis?
A. Hereditary angioedema
B. Chronic urticaria
C. Anaphylaxis
D. Acquired angioedema
Correct Answer: A
Explanation: Hereditary angioedema results from C1 inhibitor deficiency, causing recurrent
non-pitting edema without urticaria due to bradykinin accumulation.
Question 7
A 72-year-old man with a 40-year history of gastroesophageal reflux undergoes endoscopy
revealing a 5 cm segment of salmon-colored mucosa extending above the gastroesophageal
junction. Biopsy shows columnar epithelium with goblet cells. Which of the following is the
most likely diagnosis?
A. Squamous cell carcinoma
ABPath Practice Test — General Pathology, Systemic Pathology,
Hematopathology, Transfusion Medicine, Microbiology, Chemical
Pathology & Laboratory Management — 190 Multiple-Choice
Questions with Answers & Detailed Rationales
Question 1
A 58-year-old man with a 30-pack-year smoking history presents with haemoptysis and a 4
cm hilar mass. Biopsy reveals sheets of small blue round cells with nuclear moulding, scant
cytoplasm, and frequent mitotic figures. Immunohistochemistry shows positivity for CD56,
synaptophysin, and chromogranin. Which of the following is the most likely diagnosis?
A. Squamous cell carcinoma
B. Small cell carcinoma
C. Adenocarcinoma
D. Large cell neuroendocrine carcinoma
Correct Answer: B
Explanation: Small cell carcinoma is a high-grade neuroendocrine tumor with small blue
cells, nuclear molding, and neuroendocrine marker positivity. It is strongly associated with
smoking.
Question 2
A 42-year-old woman undergoes excisional biopsy of a 2.5 cm breast mass. Microscopy
shows invasive ductal carcinoma with tubule formation in >75% of the tumor, mild nuclear
,pleomorphism, and a mitotic count of 5 mitoses per 10 high-power fields. According to the
Nottingham grading system, what is the histologic grade?
A. Grade I
B. Grade II
C. Grade III
D. Grade IV
Correct Answer: A
Explanation: Tubule formation >75% (score 1), mild pleomorphism (score 1), and mitotic
count ≤7/10 HPF (score 1) yields a total score of 3, corresponding to Grade I.
Question 3
A 67-year-old man with chronic atrial fibrillation presents with acute abdominal pain and
bloody diarrhea. Colonoscopy reveals a segment of dusky, edematous mucosa in the
descending colon. Biopsy shows coagulative necrosis of the mucosa and submucosa with
preserved crypt architecture. Which of the following best describes this pathologic process?
A. Liquefactive necrosis
B. Ischemic bowel infarction
C. Ulcerative colitis
D. Pseudomembranous colitis
Correct Answer: B
Explanation: Ischemic bowel injury produces coagulative necrosis in the early phase, with
preserved tissue architecture, reflecting the ischemic insult from embolic occlusion in atrial
fibrillation.
,Question 4
A 34-year-old woman presents with fatigue, jaundice, and splenomegaly. Laboratory studies
show hemoglobin 8.2 g/dL, reticulocyte count 12%, indirect bilirubin 3.8 mg/dL, and LDH
520 U/L. Direct antiglobulin test (DAT) is positive for IgG and complement. Which of the
following is the most likely diagnosis?
A. Hereditary spherocytosis
B. Warm autoimmune hemolytic anemia
C. Cold agglutinin disease
D. Paroxysmal nocturnal hemoglobinuria
Correct Answer: B
Explanation: Warm AIHA presents with anemia, reticulocytosis, indirect hyperbilirubinemia,
elevated LDH, and a DAT positive for IgG (often with complement), reflecting extravascular
hemolysis.
Question 5
A 55-year-old man with a history of myocardial infarction undergoes autopsy. Gross
examination of the heart reveals a 3 cm area of thinning and fibrosis in the anterior left
ventricular wall. Microscopy shows replacement of myocardium by dense collagen with
scattered viable myocytes at the periphery. Which of the following best describes this
finding?
A. Acute myocardial infarction
B. Remote myocardial infarction
C. Hypertrophic cardiomyopathy
D. Myocarditis
, Correct Answer: B
Explanation: Remote myocardial infarction is characterized by replacement fibrosis with
thinning of the ventricular wall, occurring weeks to months after the ischemic event.
Question 6
A 28-year-old woman presents with recurrent episodes of swelling of the lips, tongue, and
extremities without urticaria. Symptoms began in adolescence. Laboratory studies show low
C4 and low C1 inhibitor levels. Which of the following is the most likely diagnosis?
A. Hereditary angioedema
B. Chronic urticaria
C. Anaphylaxis
D. Acquired angioedema
Correct Answer: A
Explanation: Hereditary angioedema results from C1 inhibitor deficiency, causing recurrent
non-pitting edema without urticaria due to bradykinin accumulation.
Question 7
A 72-year-old man with a 40-year history of gastroesophageal reflux undergoes endoscopy
revealing a 5 cm segment of salmon-colored mucosa extending above the gastroesophageal
junction. Biopsy shows columnar epithelium with goblet cells. Which of the following is the
most likely diagnosis?
A. Squamous cell carcinoma
