Case Report and Highlight Clues on the Diagnosis of Pilomatrical Carcinoma

Pilomatrical Carcinoma (PC) is a rare malignant adnexal tumor with matrical differentiation. Its benign counterpart (Pilomatrixoma) is diagnosed much more frequently in daily pathological practice. Both entities share genetic alterations but the malignant counterpart acquires mutations that make it develop an aggressive behavior [1]. We describe a 33-year-old man who presented with a 7 x 6 cm nodular ulcerated lesion in the left ear with markedly accelerated growth in the last month. Incisional biopsy was referred to us with suspicion of squamous cell carcinoma versus pyogenic granuloma. Histologic sections showed ulcerated fragments infiltrated by a basaloid cell proliferation interspersed with groups of “ghost cells”. The neoplastic cells were arranged in irregular sheets with infiltrative borders. Groups of Squamous cells with trichilemmal keratinization and foci of necrosis were also identified. The biopsy was diagnosed as an adnexal neoplasm with pilomatrical differentiation, suggesting its complete resection with safety margins due to the presence of aggressive characteristics. The subsequent study of the excisional biopsy showed similar characteristics to those previously described. Notoriously, focal infiltration of the auricular cartilage was identified, leading us to the undoubted diagnosis of pilomatrical carcinoma.