Pilomatrixoma of the Forearm in an Elderly Male.

Pilomatrixoma or pilomatricoma is a benign adnexal neoplasm originating from the hair matrix, the inner sheath of the hair follicle, and the hair cortex. Although it is considered rare in adults, numerous cases have been documented in the literature. We present a case of an elderly male who sought consultation due to a newly appearing nodular lesion on his left forearm. Several benign and malignant entities were included in the original differential diagnosis. High-frequency ultrasonographic features suggested a cystic neoplasm with calcification and mild intralesional vascularity. Ultimately, histopathological examination confirmed the diagnosis of pilomatricoma. In this study, our aim is to review the importance of the available diagnostic tools, such as dermoscopy, and the emerging utility of cutaneous high-frequency ultrasonography. Some rarer pathological variants are also discussed, including perforating, anetodermic, bullous and pigmented pilomatricoma. We hope that exposure to these clinical, dermoscopic, ultrasonographic, and histopathological images will encourage clinicians to consider pilomatricoma in their differential diagnosis when approaching nodular lesions, regardless of location and patient's age.