Cutaneous Oncology Flashcards

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

Answer: Infiltrative/morpheaform

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

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?

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

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

The Breslow depth is measured from which anatomic landmark?

Answer: Top of the granular layer to deepest tumor cell

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

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

Answer: S100

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

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

Answer: 0.8 mm

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

A hedgehog pathway inhibitor such as vismodegib is FDA-approved for which malignancy?

Answer: Locally advanced or metastatic basal cell carcinoma

Vismodegib targets the SMO component of the hedgehog pathway driving advanced BCC.

Which recurrent gene fusion is characteristic of dermatofibrosarcoma protuberans?

Answer: COL1A1-PDGFB

DFSP is driven by the COL1A1-PDGFB fusion, making imatinib effective in advanced disease.