ABD Cutaneous Oncology 2

Question 1

Which histologic subtype of basal cell carcinoma carries the highest risk of subclinical extension and local recurrence?

Accepted Answer

Infiltrative/morpheaform

Answer

Infiltrative and morpheaform BCCs have aggressive growth patterns with poorly defined margins and high recurrence risk.

Question 2

A 62-year-old man has a 2.5 cm squamous cell carcinoma on the ear with perineural invasion. Which feature most upgrades his risk?

Accepted Answer

All contribute but PNI of large nerves is key high-risk

Answer

Large-caliber perineural invasion, ear location, and size >2 cm are all high-risk features, with large-nerve PNI being especially adverse.

Question 3

The Breslow depth is measured from which anatomic landmark?

Accepted Answer

Top of the granular layer to deepest tumor cell

Answer

Breslow thickness is measured from the top of the granular layer to the deepest invasive melanoma cell.

Question 4

Which immunostain is most useful to confirm melanocytic differentiation in a spindle-cell (desmoplastic) melanoma?

Accepted Answer

S100

Answer

Desmoplastic melanoma is often HMB-45 and Melan-A negative but reliably S100 positive.

Question 5

For melanoma, sentinel lymph node biopsy is generally recommended starting at what Breslow thickness (with no other high-risk features)?

Accepted Answer

0.8 mm

Answer

SLNB is considered for melanomas ≥0.8 mm or thinner lesions with ulceration.

American Board of Dermatology (ABD) Practice Test