Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

We present a rare case of basal cell carcinoma (BCC) overlying a dermatofibroma in an African American patient. The patient, a 71-year-old female, presented with a red to dark brown papule on her right lower leg, alongside multiple dermatofibromas. Due to the irregularity in pigment, the lesion was subsequently biopsied. Microscopic examination of the biopsy revealed features consistent with dermatofibroma with overlying BCC, including downward basaloid aggregates, peripheral palisading, and retraction artifacts. Immunohistochemical stains supported the diagnosis which were positive for p40 and Ber-EP4 in the superficial basaloid cells and Factor XIIIa in the dermal spindle cells. The patient underwent wide local excision, tolerated well, and followed up six months later without any concerns.

The discussion emphasizes the rarity of true BCCs overlying dermatofibromas, which are much less prevalent and much fewer reported cases compared to more commonly seen BCC-like changes (hyperplasia) seen in dermatofibromas, which typically lack malignant potential. Differential diagnoses include various histologic mimickers of BCCs such as follicular induction over DF, benign hair germ tumors, and basaloid follicular hamartoma. This highlights the importance of histopathologic examination for accurate diagnosis, and identifying specific characteristics that differentiate true BCC from other mimickers. While dermatofibromas are common, changes in size, irregularities in shape or color, or symptomatic lesions should prompt histopathological investigation. While rare, this case also underscores the significance of recognizing diverse presentations across skin tones and the need for continued education to ensure early diagnosis and optimal patient care, particularly in skin of color populations. Further research is warranted to elucidate underlying mechanisms and implications in similar cases.

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Valerie Callender, MD, FAAD