Tricholemmoma and Tricholemmal Carcinoma and Cowden Syndrome

Tricholemmoma and tricholemmal carcinoma were benign and malignant tumors of the hair follicle, respectively, typically found on the head and neck of elderly individuals. Tricholemmoma could present as solitary or multiple papules and was often linked to Cowden syndrome, a rare genetic disorder characterized by multiple hamartomas and neoplastic growths. Tricholemmal carcinoma appeared as exophytic or polypoid nodules. Dermoscopic features of tricholemmoma included keratin masses with perivascular whitish halos, while tricholemmal carcinoma showed a polymorphous vascular pattern, white-yellowish areas, and ulceration. Both conditions required differentiation from basal cell carcinoma, squamous cell carcinoma, keratoacanthoma, and viral warts.