ABD Cutaneous Oncology 3

Question 1

Merkel cell carcinoma is most strongly associated with which infectious agent?

Accepted Answer

Merkel cell polyomavirus

Answer

Merkel cell polyomavirus integration drives the majority of Merkel cell carcinomas.

Question 2

Which immunostain shows a characteristic paranuclear dot pattern in Merkel cell carcinoma?

Accepted Answer

CK20

Answer

CK20 typically shows perinuclear dot-like staining while TTF-1 is negative, helping distinguish MCC from metastatic small cell lung cancer.

Question 3

The first-line systemic therapy class for advanced Merkel cell carcinoma is:

Accepted Answer

PD-1/PD-L1 checkpoint inhibitors

Answer

Avelumab and pembrolizumab (PD-1/PD-L1 blockade) are first-line for advanced MCC.

Question 4

Extramammary Paget disease of the vulva most often stains positively for which marker?

Accepted Answer

CK7

Answer

The intraepidermal adenocarcinoma cells of EMPD are characteristically CK7 positive.

Question 5

Which finding on a mycosis fungoides biopsy is most specific for the diagnosis?

Accepted Answer

Pautrier microabscesses

Answer

Pautrier microabscesses—intraepidermal collections of atypical lymphocytes—are highly specific for mycosis fungoides.

American Board of Dermatology (ABD) Practice Test