LATEST PATHOLOGY - SELECTIVE
PATHOLOGY CERTIFICATION EXAM OFFERED
BY AMERICAN BOARD OF PATHOLOGY (ABMS)
| COMPLETE EXAM Q&A WITH RATIONALES
1. A 55-year-old man with a history of smoking
presents with a well-circumscribed, firm, yellow
nodule on his forehead. Excision shows a dermal
tumor composed of lobules of mature adipocytes with
a fibrovascular stroma. There is no nuclear atypia or
lipoblasts. What is the most likely diagnosis?
A) Lipoma (conventional)
B) Atypical lipomatous tumor (well-differentiated
liposarcoma)
C) Fibrolipoma
D) Spindle cell lipoma
Correct answer: A
Rationale: Conventional lipoma is a benign tumor of
mature adipocytes, often in subcutaneous tissue. No
atypia, no lipoblasts. Atypical lipomatous tumor (B)
shows scattered atypical cells and can occur in deep
soft tissue.
,2. A 45-year-old woman presents with a slow-
growing, painless mass in the thigh. MRI shows a
well-circumscribed, fatty mass with thin septa.
Excision shows mature adipocytes with scattered
atypical stromal cells with hyperchromatic nuclei. No
lipoblasts or mitotic figures. What is the most likely
diagnosis?
A) Atypical lipomatous tumor (well-differentiated
liposarcoma)
B) Lipoma
C) Spindle cell lipoma
D) Pleomorphic liposarcoma
Correct answer: A
Rationale: Atypical lipomatous tumor (ALT) / well-
differentiated liposarcoma (WDLPS) shows mature
adipocytes with scattered atypical cells
(hyperchromatic, enlarged nuclei). No lipoblasts.
MDM2 amplification (by FISH) is diagnostic.
3. A 50-year-old man presents with a deep-seated,
large (15 cm), firm mass in the retroperitoneum.
Resection shows a multilobulated, yellow-tan mass
with fibrous bands. Histology shows atypical
adipocytes, lipoblasts, and a spindle cell component.
MDM2 and CDK4 are positive by IHC. What is the
most likely diagnosis?
,A) Dedifferentiated liposarcoma
B) Well-differentiated liposarcoma (WDLPS)
C) Pleomorphic liposarcoma
D) Myxoid liposarcoma
Correct answer: A
Rationale: Dedifferentiated liposarcoma (in
retroperitoneum) shows a transition from WDLPS
(MDM2+) to a non-lipogenic high-grade sarcoma
(often undifferentiated). MDM2/CDK4 positivity is
retained. Worse prognosis than WDLPS.
4. A 35-year-old man presents with a painless mass in
the thigh. MRI shows a well-circumscribed, myxoid
mass. Excision shows a myxoid liposarcoma (MLS).
What is the characteristic genetic alteration?
A) FUS-DDIT3 (CHOP) fusion (t(12;16))
B) MDM2 amplification (12q15)
C) EWSR1-ATF1 fusion
D) COL1A1-PDGFB fusion
Correct answer: A
Rationale: Myxoid liposarcoma (MLS) has
t(12;16)(q13;p11) → FUS-DDIT3 (CHOP) fusion.
Pleomorphic liposarcoma (C) has complex karyotype.
, MLS has a prominent myxoid stroma and chicken-
wire vasculature.
5. A 60-year-old woman presents with a firm, slow-
growing mass in the thigh. MRI shows a well-
demarcated, intramuscular mass. Biopsy shows a
spindle cell sarcoma with herringbone pattern,
nuclear pleomorphism, and mitotic figures. The
tumor cells are positive for smooth muscle actin and
desmin, negative for S-100 and CD34. What is the
most likely diagnosis?
A) Leiomyosarcoma
B) Fibrosarcoma
C) Undifferentiated pleomorphic sarcoma (UPS)
D) Synovial sarcoma
Correct answer: A
Rationale: Leiomyosarcoma (smooth muscle origin) is
positive for SMA, desmin, and h-caldesmon.
Herringbone pattern is classic for fibrosarcoma (B)
but fibrosarcoma is negative for desmin. UPS (C)
lacks smooth muscle markers.
6. A 40-year-old man presents with a deep-seated
mass in the thigh. Biopsy shows a storiform pattern of
spindle cells with a prominent hemangiopericytoma-
PATHOLOGY CERTIFICATION EXAM OFFERED
BY AMERICAN BOARD OF PATHOLOGY (ABMS)
| COMPLETE EXAM Q&A WITH RATIONALES
1. A 55-year-old man with a history of smoking
presents with a well-circumscribed, firm, yellow
nodule on his forehead. Excision shows a dermal
tumor composed of lobules of mature adipocytes with
a fibrovascular stroma. There is no nuclear atypia or
lipoblasts. What is the most likely diagnosis?
A) Lipoma (conventional)
B) Atypical lipomatous tumor (well-differentiated
liposarcoma)
C) Fibrolipoma
D) Spindle cell lipoma
Correct answer: A
Rationale: Conventional lipoma is a benign tumor of
mature adipocytes, often in subcutaneous tissue. No
atypia, no lipoblasts. Atypical lipomatous tumor (B)
shows scattered atypical cells and can occur in deep
soft tissue.
,2. A 45-year-old woman presents with a slow-
growing, painless mass in the thigh. MRI shows a
well-circumscribed, fatty mass with thin septa.
Excision shows mature adipocytes with scattered
atypical stromal cells with hyperchromatic nuclei. No
lipoblasts or mitotic figures. What is the most likely
diagnosis?
A) Atypical lipomatous tumor (well-differentiated
liposarcoma)
B) Lipoma
C) Spindle cell lipoma
D) Pleomorphic liposarcoma
Correct answer: A
Rationale: Atypical lipomatous tumor (ALT) / well-
differentiated liposarcoma (WDLPS) shows mature
adipocytes with scattered atypical cells
(hyperchromatic, enlarged nuclei). No lipoblasts.
MDM2 amplification (by FISH) is diagnostic.
3. A 50-year-old man presents with a deep-seated,
large (15 cm), firm mass in the retroperitoneum.
Resection shows a multilobulated, yellow-tan mass
with fibrous bands. Histology shows atypical
adipocytes, lipoblasts, and a spindle cell component.
MDM2 and CDK4 are positive by IHC. What is the
most likely diagnosis?
,A) Dedifferentiated liposarcoma
B) Well-differentiated liposarcoma (WDLPS)
C) Pleomorphic liposarcoma
D) Myxoid liposarcoma
Correct answer: A
Rationale: Dedifferentiated liposarcoma (in
retroperitoneum) shows a transition from WDLPS
(MDM2+) to a non-lipogenic high-grade sarcoma
(often undifferentiated). MDM2/CDK4 positivity is
retained. Worse prognosis than WDLPS.
4. A 35-year-old man presents with a painless mass in
the thigh. MRI shows a well-circumscribed, myxoid
mass. Excision shows a myxoid liposarcoma (MLS).
What is the characteristic genetic alteration?
A) FUS-DDIT3 (CHOP) fusion (t(12;16))
B) MDM2 amplification (12q15)
C) EWSR1-ATF1 fusion
D) COL1A1-PDGFB fusion
Correct answer: A
Rationale: Myxoid liposarcoma (MLS) has
t(12;16)(q13;p11) → FUS-DDIT3 (CHOP) fusion.
Pleomorphic liposarcoma (C) has complex karyotype.
, MLS has a prominent myxoid stroma and chicken-
wire vasculature.
5. A 60-year-old woman presents with a firm, slow-
growing mass in the thigh. MRI shows a well-
demarcated, intramuscular mass. Biopsy shows a
spindle cell sarcoma with herringbone pattern,
nuclear pleomorphism, and mitotic figures. The
tumor cells are positive for smooth muscle actin and
desmin, negative for S-100 and CD34. What is the
most likely diagnosis?
A) Leiomyosarcoma
B) Fibrosarcoma
C) Undifferentiated pleomorphic sarcoma (UPS)
D) Synovial sarcoma
Correct answer: A
Rationale: Leiomyosarcoma (smooth muscle origin) is
positive for SMA, desmin, and h-caldesmon.
Herringbone pattern is classic for fibrosarcoma (B)
but fibrosarcoma is negative for desmin. UPS (C)
lacks smooth muscle markers.
6. A 40-year-old man presents with a deep-seated
mass in the thigh. Biopsy shows a storiform pattern of
spindle cells with a prominent hemangiopericytoma-
