Malignant proliferating trichilemmal tumor: a case report of a rare clinicopathological conundrum

Proliferating trichilemmal tumors are rare, generally solitary, benign tumors arising from the hair’s outer root sheath with trichilemmal keratinization. These tumors are predominantly found on the head, neck, and face of elderly females; the inguinal region is a highly unusual site of involvement. Malignant change in this tumor is rare, histologically mimicking squamous cell carcinoma. Metastatic malignant proliferating trichilemmal tumor requires a high index of suspicion for diagnosis and accurate histopathological reporting for timely intervention. Here, we report the case of a 65-yearold man presenting with nodular-ulcerative lesions in the groin, clinically confused with hidradenitis suppurativa and histologically with squamous cell carcinoma. He was finally diagnosed with an inoperable metastatic stage of malignant proliferating trichilemmal tumor and was treated with palliative care. This case highlights the innocuous clinical appearance of such lesions that might delay the management of this fulminant tumor.