ABPATH-AMERICAN BOARD OF PATHOLOGY AP/CP
ERTIFICATION EXAM | ALL QUESTIONS AND
ANSWERS | A+ GRADED | COMPREHENSIVE EXAM
GUIDE 2026/2027
1. A 58-year-old patient presents with fatigue, weight loss, and persistent
lymphadenopathy. A lymph node biopsy demonstrates diffuse proliferation of large
atypical lymphoid cells. The cells express CD20, PAX5, and BCL6, with a high Ki-67
proliferation index. Which diagnosis is most consistent with these findings?
A. Classical Hodgkin lymphoma
B. Diffuse large B-cell lymphoma
C. Mantle cell lymphoma
D. Follicular lymphoma
Answer: B
Rationale: Diffuse large B-cell lymphoma is characterized by a diffuse proliferation of large
mature B cells expressing B-cell markers such as CD20 and PAX5. BCL6 expression and a
high Ki-67 index commonly support the diagnosis in the appropriate morphologic setting.
2. A bone marrow aspirate shows blasts that are positive for myeloperoxidase and CD13
but negative for CD19 and cytoplasmic CD3. Which lineage is best supported?
A. Myeloid
B. B lymphoid
C. T lymphoid
D. Plasma cell
Answer: A
Rationale: Myeloperoxidase is a key marker of myeloid differentiation. CD13 further supports
myeloid lineage, whereas the absence of B- and T-lineage markers argues against lymphoid
differentiation.
3. A 42-year-old woman has microcytic anemia. Her ferritin is decreased, total iron-
binding capacity is increased, and transferrin saturation is reduced. Which diagnosis is
most likely?
A. Anemia of chronic inflammation
B. Sideroblastic anemia
C. Iron deficiency anemia
D. Thalassemia major
Answer: C
,Rationale: Low ferritin, increased total iron-binding capacity, and reduced transferrin
saturation are classic laboratory findings of iron deficiency anemia.
4. A renal biopsy from a patient with nephrotic syndrome demonstrates diffuse thickening
of glomerular capillary walls without significant hypercellularity. Immunofluorescence
shows granular IgG and C3 along the peripheral capillary loops. Which condition is most
likely?
A. Minimal change disease
B. Membranous nephropathy
C. IgA nephropathy
D. Postinfectious glomerulonephritis
Answer: B
Rationale: Membranous nephropathy produces diffuse glomerular basement membrane
thickening with granular capillary-loop staining for IgG and complement.
5. A thyroid nodule contains papillary structures lined by cells with nuclear clearing,
nuclear grooves, and intranuclear cytoplasmic pseudoinclusions. What is the most likely
diagnosis?
A. Follicular adenoma
B. Medullary thyroid carcinoma
C. Papillary thyroid carcinoma
D. Anaplastic thyroid carcinoma
Answer: C
Rationale: Nuclear clearing, grooves, and intranuclear pseudoinclusions are characteristic
cytologic features of papillary thyroid carcinoma and are more diagnostically important than
the papillary architecture alone.
6. A patient with suspected acute promyelocytic leukemia has abnormal promyelocytes
containing numerous Auer rods. Which molecular abnormality should be urgently
investigated?
A. BCR::ABL1
B. PML::RARA
C. MYC rearrangement
D. JAK2 V617F
Answer: B
Rationale: Acute promyelocytic leukemia is associated with PML::RARA, most commonly
resulting from t(15;17). Rapid recognition is clinically critical because prompt therapy can
reduce the risk of fatal coagulopathy.
,7. A breast carcinoma is composed of infiltrative glands and nests within desmoplastic
stroma. The tumor cells are strongly positive for cytokeratin and show loss of membranous
E-cadherin expression. Which diagnosis is favored?
A. Invasive lobular carcinoma
B. Invasive ductal carcinoma
C. Mucinous carcinoma
D. Metaplastic carcinoma
Answer: A
Rationale: Invasive lobular carcinoma classically demonstrates discohesive cells and loss of
E-cadherin expression due to alterations involving CDH1.
8. A 67-year-old man has persistent erythrocytosis. Testing demonstrates a JAK2 V617F
mutation. Which diagnosis should be strongly considered?
A. Essential thrombocythemia
B. Polycythemia vera
C. Primary myelofibrosis
D. Chronic myeloid leukemia
Answer: B
Rationale: JAK2 mutations are strongly associated with polycythemia vera and support a
clonal myeloproliferative neoplasm in a patient with otherwise unexplained erythrocytosis.
9. A colon biopsy demonstrates chronic active colitis with crypt architectural distortion and
crypt abscesses. Which additional finding would most strongly support ulcerative colitis?
A. Transmural inflammation with fistula formation
B. Noncaseating granulomas
C. Continuous mucosal involvement beginning at the rectum
D. Skip lesions throughout the gastrointestinal tract
Answer: C
Rationale: Ulcerative colitis typically produces continuous mucosal inflammation beginning
in the rectum and extending proximally to varying degrees. Transmural inflammation and
skip lesions favor Crohn disease.
10. A patient develops jaundice several days after receiving an incompatible blood
transfusion. Laboratory testing demonstrates a positive direct antiglobulin test and
evidence of hemolysis. Which process is most likely?
A. Delayed hemolytic transfusion reaction
B. Acute hemolytic transfusion reaction
C. Febrile nonhemolytic transfusion reaction
D. Transfusion-associated circulatory overload
, Answer: B
Rationale: An acute hemolytic transfusion reaction can result from ABO incompatibility and
is characterized by rapid intravascular hemolysis, often with a positive direct antiglobulin test
and clinical deterioration during or shortly after transfusion.
11. A prostate biopsy demonstrates crowded malignant glands with prominent nucleoli and
absence of the basal cell layer. Which immunohistochemical combination is most
supportive of prostatic adenocarcinoma?
A. PSA positive and p63 positive in tumor cells
B. NKX3.1 positive with absence of basal-cell markers
C. TTF-1 positive and Napsin A positive
D. GATA3 positive and uroplakin positive
Answer: B
Rationale: NKX3.1 is a highly useful marker of prostatic differentiation, while malignant
prostatic glands characteristically lack the basal cell layer demonstrated by markers such as
p63 and high-molecular-weight cytokeratins.
12. A bone marrow biopsy from a patient with suspected acute leukemia is markedly
hypercellular and contains 35% blasts. Which finding establishes acute leukemia in the
appropriate clinical context?
A. Presence of any anemia
B. Blast percentage meeting diagnostic criteria for acute leukemia
C. Mild thrombocytopenia alone
D. Increased reticulocyte count
Answer: B
Rationale: Acute leukemia is defined using established blast thresholds and/or specific
defining genetic abnormalities depending on the disease entity. Morphology must be
integrated with immunophenotyping and genetic studies.
13. A cerebrospinal fluid specimen contains numerous neutrophils, markedly decreased
glucose, and elevated protein. Which process is most consistent with these findings?
A. Bacterial meningitis
B. Viral meningitis
C. Multiple sclerosis
D. Viral encephalitis
Answer: A
Rationale: Bacterial meningitis typically produces neutrophilic pleocytosis, increased protein,
and decreased CSF glucose. Viral infections more commonly produce lymphocytic pleocytosis
with relatively preserved glucose.
ERTIFICATION EXAM | ALL QUESTIONS AND
ANSWERS | A+ GRADED | COMPREHENSIVE EXAM
GUIDE 2026/2027
1. A 58-year-old patient presents with fatigue, weight loss, and persistent
lymphadenopathy. A lymph node biopsy demonstrates diffuse proliferation of large
atypical lymphoid cells. The cells express CD20, PAX5, and BCL6, with a high Ki-67
proliferation index. Which diagnosis is most consistent with these findings?
A. Classical Hodgkin lymphoma
B. Diffuse large B-cell lymphoma
C. Mantle cell lymphoma
D. Follicular lymphoma
Answer: B
Rationale: Diffuse large B-cell lymphoma is characterized by a diffuse proliferation of large
mature B cells expressing B-cell markers such as CD20 and PAX5. BCL6 expression and a
high Ki-67 index commonly support the diagnosis in the appropriate morphologic setting.
2. A bone marrow aspirate shows blasts that are positive for myeloperoxidase and CD13
but negative for CD19 and cytoplasmic CD3. Which lineage is best supported?
A. Myeloid
B. B lymphoid
C. T lymphoid
D. Plasma cell
Answer: A
Rationale: Myeloperoxidase is a key marker of myeloid differentiation. CD13 further supports
myeloid lineage, whereas the absence of B- and T-lineage markers argues against lymphoid
differentiation.
3. A 42-year-old woman has microcytic anemia. Her ferritin is decreased, total iron-
binding capacity is increased, and transferrin saturation is reduced. Which diagnosis is
most likely?
A. Anemia of chronic inflammation
B. Sideroblastic anemia
C. Iron deficiency anemia
D. Thalassemia major
Answer: C
,Rationale: Low ferritin, increased total iron-binding capacity, and reduced transferrin
saturation are classic laboratory findings of iron deficiency anemia.
4. A renal biopsy from a patient with nephrotic syndrome demonstrates diffuse thickening
of glomerular capillary walls without significant hypercellularity. Immunofluorescence
shows granular IgG and C3 along the peripheral capillary loops. Which condition is most
likely?
A. Minimal change disease
B. Membranous nephropathy
C. IgA nephropathy
D. Postinfectious glomerulonephritis
Answer: B
Rationale: Membranous nephropathy produces diffuse glomerular basement membrane
thickening with granular capillary-loop staining for IgG and complement.
5. A thyroid nodule contains papillary structures lined by cells with nuclear clearing,
nuclear grooves, and intranuclear cytoplasmic pseudoinclusions. What is the most likely
diagnosis?
A. Follicular adenoma
B. Medullary thyroid carcinoma
C. Papillary thyroid carcinoma
D. Anaplastic thyroid carcinoma
Answer: C
Rationale: Nuclear clearing, grooves, and intranuclear pseudoinclusions are characteristic
cytologic features of papillary thyroid carcinoma and are more diagnostically important than
the papillary architecture alone.
6. A patient with suspected acute promyelocytic leukemia has abnormal promyelocytes
containing numerous Auer rods. Which molecular abnormality should be urgently
investigated?
A. BCR::ABL1
B. PML::RARA
C. MYC rearrangement
D. JAK2 V617F
Answer: B
Rationale: Acute promyelocytic leukemia is associated with PML::RARA, most commonly
resulting from t(15;17). Rapid recognition is clinically critical because prompt therapy can
reduce the risk of fatal coagulopathy.
,7. A breast carcinoma is composed of infiltrative glands and nests within desmoplastic
stroma. The tumor cells are strongly positive for cytokeratin and show loss of membranous
E-cadherin expression. Which diagnosis is favored?
A. Invasive lobular carcinoma
B. Invasive ductal carcinoma
C. Mucinous carcinoma
D. Metaplastic carcinoma
Answer: A
Rationale: Invasive lobular carcinoma classically demonstrates discohesive cells and loss of
E-cadherin expression due to alterations involving CDH1.
8. A 67-year-old man has persistent erythrocytosis. Testing demonstrates a JAK2 V617F
mutation. Which diagnosis should be strongly considered?
A. Essential thrombocythemia
B. Polycythemia vera
C. Primary myelofibrosis
D. Chronic myeloid leukemia
Answer: B
Rationale: JAK2 mutations are strongly associated with polycythemia vera and support a
clonal myeloproliferative neoplasm in a patient with otherwise unexplained erythrocytosis.
9. A colon biopsy demonstrates chronic active colitis with crypt architectural distortion and
crypt abscesses. Which additional finding would most strongly support ulcerative colitis?
A. Transmural inflammation with fistula formation
B. Noncaseating granulomas
C. Continuous mucosal involvement beginning at the rectum
D. Skip lesions throughout the gastrointestinal tract
Answer: C
Rationale: Ulcerative colitis typically produces continuous mucosal inflammation beginning
in the rectum and extending proximally to varying degrees. Transmural inflammation and
skip lesions favor Crohn disease.
10. A patient develops jaundice several days after receiving an incompatible blood
transfusion. Laboratory testing demonstrates a positive direct antiglobulin test and
evidence of hemolysis. Which process is most likely?
A. Delayed hemolytic transfusion reaction
B. Acute hemolytic transfusion reaction
C. Febrile nonhemolytic transfusion reaction
D. Transfusion-associated circulatory overload
, Answer: B
Rationale: An acute hemolytic transfusion reaction can result from ABO incompatibility and
is characterized by rapid intravascular hemolysis, often with a positive direct antiglobulin test
and clinical deterioration during or shortly after transfusion.
11. A prostate biopsy demonstrates crowded malignant glands with prominent nucleoli and
absence of the basal cell layer. Which immunohistochemical combination is most
supportive of prostatic adenocarcinoma?
A. PSA positive and p63 positive in tumor cells
B. NKX3.1 positive with absence of basal-cell markers
C. TTF-1 positive and Napsin A positive
D. GATA3 positive and uroplakin positive
Answer: B
Rationale: NKX3.1 is a highly useful marker of prostatic differentiation, while malignant
prostatic glands characteristically lack the basal cell layer demonstrated by markers such as
p63 and high-molecular-weight cytokeratins.
12. A bone marrow biopsy from a patient with suspected acute leukemia is markedly
hypercellular and contains 35% blasts. Which finding establishes acute leukemia in the
appropriate clinical context?
A. Presence of any anemia
B. Blast percentage meeting diagnostic criteria for acute leukemia
C. Mild thrombocytopenia alone
D. Increased reticulocyte count
Answer: B
Rationale: Acute leukemia is defined using established blast thresholds and/or specific
defining genetic abnormalities depending on the disease entity. Morphology must be
integrated with immunophenotyping and genetic studies.
13. A cerebrospinal fluid specimen contains numerous neutrophils, markedly decreased
glucose, and elevated protein. Which process is most consistent with these findings?
A. Bacterial meningitis
B. Viral meningitis
C. Multiple sclerosis
D. Viral encephalitis
Answer: A
Rationale: Bacterial meningitis typically produces neutrophilic pleocytosis, increased protein,
and decreased CSF glucose. Viral infections more commonly produce lymphocytic pleocytosis
with relatively preserved glucose.
