Early Pilomatrix Carcinoma: A Case Report With Emphasis on Molecular Pathology and Review of the Literature.

Pilomatrix carcinoma is a rare adnexal tumor with origin from the germinative matrical cells of the hair follicle. Clinically, it presents as a solitary lesion commonly found in the head and neck region and upper back. The tumors cannot be distinguished by their clinical appearance only and frequently are mistaken for cysts. Histopathologic examination provides the definitive diagnosis in most cases. Such carcinomas are aggressive neoplasms with a high probability of local recurrence and distant metastasis. Assessment of the Wnt signaling pathway components such as β-catenin, lymphoid enhancer-binding factor 1 (LEF-1) and caudal-related homeobox transcription factor 2 (CDX-2) potentially can be used for diagnostic purposes and targeted therapy. Herein, we report a rare and unique case of early pilomatrix carcinoma with intralesional melanocytes. We also review the molecular pathology and pathogenesis of these carcinomas as well as the significance of early diagnosis in their management.