ABPath Dermatopathology 3

Question 1

Which molecular alteration is found in approximately 40–60% of cutaneous melanomas arising on intermittently sun-exposed skin?

Accepted Answer

BRAF V600E mutation

Answer

BRAF V600E mutations occur in approximately 40–60% of cutaneous melanomas, particularly those on intermittently sun-exposed skin, making BRAF the most common actionable driver mutation.

Question 2

A compound melanocytic lesion shows large epithelioid cells with abundant cytoplasm containing fine 'dusty' melanin pigment arranged in nests, with a pushing border into the deep dermis but no significant atypia or mitoses. This best describes:

Accepted Answer

Deep penetrating nevus

Answer

Deep penetrating nevus is characterized by large epithelioid-to-spindle melanocytes with abundant dusty melanin pigment arranged in nests and fascicles, extending deeply into the dermis with a pushing border but without significant atypia.

Question 3

The t(X;18)(p11;q11) translocation producing an SS18-SSX fusion gene is the defining molecular alteration of:

Accepted Answer

Synovial sarcoma

Answer

Synovial sarcoma is defined by the t(X;18)(p11;q11) translocation creating SS18-SSX1 or SS18-SSX2 fusion genes, which is diagnostic and found in virtually all cases regardless of morphology.

Question 4

Donovan bodies (Klebsiella granulomatis within macrophages) in granuloma inguinale are best demonstrated with:

Accepted Answer

Giemsa stain

Answer

Donovan bodies appear as bipolar-staining intracytoplasmic rod-shaped organisms with a 'safety pin' appearance, best demonstrated with Giemsa stain on tissue smears or biopsies.

Question 5

A skin biopsy from an HIV-positive patient shows lobular capillary proliferation with plump endothelial cells, neutrophils, and granular eosinophilic material best identified by Warthin-Starry stain. This is most consistent with:

Accepted Answer

Bacillary angiomatosis

Answer

Bacillary angiomatosis (caused by Bartonella henselae or B. quintana) shows lobular vascular proliferation with plump endothelial cells, neutrophils, and granular bacterial clumps highlighted by Warthin-Starry stain.

American Board of Pathology (ABPath) Practice Test

American Board of Pathology (ABPath) Practice Test

ABPath Dermatopathology 3