Abstract
Trichilemmal carcinoma (TC) is a rare malignant epithelial neoplasm with outer root sheath differentiation. Tumors most often arise from transformation of a trichilemmal (or pilar) cyst and usually present on the head and neck regions due to the higher density of skin adnexal structures and higher degree of sun exposure. In this report, we describe a case of TC presenting as a large, fungating mass covering almost the entire scalp of a 58-year-old female. The patient presented to the emergency department after emergency personnel was deployed to her house and found her with a large, actively bleeding scalp mass. She reported that the lipoma first appeared years ago and became infected but resolved completely before returning and growing progressively over the last 3-4 years. She also reported a 50 pound weight loss in the past year. On examination, the mass was grossly necrotic and foul smelling with areas of hemorrhage spanning the temporal, parietal, and occipital scalp, with an additionally noted submental mass. Imaging performed demonstrated a 20.8 x 10.9 cm mass with no evidence of intracranial extension or bony destruction. Excisional biopsy was performed and was consistent with a malignant proliferating trichilemmal tumor, prompting wide excision of the mass, which grossly weighed 1,730 grams and focally extended to the deep margin. The submental mass was consistent with a trichilemmal cyst. The final diagnosis of the scalp mass was TC. This case represents an extreme presentation of a rare malignancy arising from a trichilemmal cyst.
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