Aggressive Pilomatrixoma of the Scalp in a Geriatric Patient: A Rare Occurrence

Abstract

Pilomatrixoma is a benign cutaneous adnexal neoplasm that arises from the hair matrix. This lesion is typically observed in the first two decades of life, with most cases occurring before the age of 20. However, it is rare in the elderly. While aggressive and malignant variants of pilomatrixoma exist, they are rarely reported compared to their benign counterparts. In this case, we present an instance of aggressive pilomatrixoma in a 90-year-old female. The patient exhibited a large ulceroproliferative growth on the scalp. A preliminary biopsy was performed, followed by wide local excision. Both the biopsy and excision specimens exhibited characteristics of pilomatrixoma, with a focal infiltrative growth pattern and moderate nuclear atypia. Features indicative of malignancy, such as geographic necrosis, brisk mitosis, atypical mitosis, vascular invasion, and perineural invasion, were not observed. Therefore, the diagnosis of aggressive pilomatrixoma was made. Wide local excision and subsequent skin grafting were conducted, with no involvement of deeper subcutaneous tissue and intact pericranium. The patient is currently faring well during follow-up. This case underscores the importance of meticulous histopathological examination for distinguishing aggressive variants, as they carry a higher risk of recurrence and aid in distinguishing aggressive pilomatrixoma from carcinoma. Failure to recognise the aggressive variant may result in inadequate management.