Race for the Case

Race for the Case is a clinical quiz feature published quarterly in DermWorld Directions in Residency — and right here!

Answer the questions below to enter. Looking for the Summer 2025 answers? Review them now. To submit cases and questions, email Emily Margosian at emargosian@aad.org.

Diagnose this new case by Madeleine Medvedev, MD, and Alejando Barrera-Godínez, MD, IFAAD

A 22-year-old male patient with no significant past medical history presents to clinic with a “spot on the scalp.” It was present since birth, though over the past few years has been growing and bleeding. Initially, it was not bothersome though more recently can be tender on palpation. The patient denies a personal or family history of skin cancer.

1. Biopsy showed a typical “fjords and fronds” appearance. What other cell type would be present (usually within the cores of the fronds)?

2. Based on the diagnosis, within what primary lesion did this occur?

3. What is the most common secondary neoplasm that can occur within this patient’s primary lesion?

4. What is the main histologic differential diagnosis of this lesion? On histology, it would show a maze-like configuration and usually occurs on the vulva/perineum.

5. If this lesion was not removed via biopsy for this patient, is there a high likelihood of malignant transformation?

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