Random Dermatology MCQ - Squamous Cell Carcinoma (SCC)

A 75-year-old fair-skinned farmer presents with a persistent, hyperkeratotic, erythematous plaque on the pinna of his right ear. The lesion is indurated, bleeds easily with minimal trauma, and has been slowly enlarging over the past year.

RANDOM DERMATOLOGY MCQS

9/27/20251 min read

a man riding a skateboard down the side of a ramp
a man riding a skateboard down the side of a ramp

A 75-year-old fair-skinned farmer presents with a persistent, hyperkeratotic, erythematous plaque on the pinna of his right ear. The lesion is indurated, bleeds easily with minimal trauma, and has been slowly enlarging over the past year. A biopsy confirms a invasive squamous cell carcinoma. Which of the following associated findings in the biopsy specimen is the most significant prognostic indicator for an increased risk of local recurrence and metastasis?

A) Perineural invasion
B) Adjacent actinic keratosis
C) Dense inflammatory infiltrate
D) Focal acantholysis
E) Solar elastosis

Correct Answer: A) Perineural invasion

Explanation

This patient has a squamous cell carcinoma (SCC) on a high-risk site (the ear), with a classic history of a non-healing, bleeding, indurated plaque in a sun-exposed area.

Key High-Risk Features for SCC:

The most important prognostic factors for metastasis and local recurrence in cutaneous SCC are:

  1. Perineural invasion (PNI): This is one of the strongest predictors of aggressive behavior, associated with higher rates of recurrence and metastasis.

  2. Tumor depth and thickness: Invasion >6 mm (or >2 mm if on the lip or ear) or into the subcutaneous fat.

  3. Poor histological differentiation: High-grade tumors with marked cytologic atypia and numerous mitoses.

  4. Anatomic location: High-risk sites include the ear, lip, temple, scalp, hands, and feet.

  5. Immunosuppression.

  6. Rapid growth or recurrence.

Why Not Other Options?

  • (B) Adjacent actinic keratosis: This indicates the SCC arose from a precursor lesion (field cancerization) but does not confer a worse prognosis for the invasive carcinoma itself.

  • (C) Dense inflammatory infiltrate: This is a common host response and is not a specific prognostic indicator.

  • (D) Focal acantholysis: This describes an "acantholytic" SCC variant, which may have a slightly higher metastatic potential but is not as significant a risk factor as PNI.

  • (E) Solar elastosis: This is a marker of chronic UV damage and is the background for most SCCs, but it is not a prognostic factor for an individual tumor's behavior.

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