Proliferating Giant Pilomatrixoma: A Case Report

TL;DR

A 36-year-old woman had a large, fast-growing pilomatrixoma on her cheek, which was surgically removed and diagnosed as a rare giant and proliferative variant.

Contribution

This case report highlights a rare combination of giant and proliferative pilomatrixoma variants in an adult.

Findings

The tumor was classified as a giant pilomatrixoma due to its size (≥4 cm).

Histopathology confirmed a proliferative subtype, which is uncommon in adults.

Complete surgical excision is critical to prevent recurrence or malignant transformation.

Abstract

Pilomatrixoma is a benign adnexal tumor, frequently observed in pediatric and young adult populations, and originates from the hair follicle matrix. While the most common clinical presentation is a subcutaneous nodule, multiple clinicopathological variants have been identified. One such variant is the giant pilomatrixoma, defined by a size of 4 cm or greater, which may mimic malignant neoplasms such as angiosarcoma or amelanotic melanoma in adults. We present the case of a 36-year-old female patient who presented with an exophytic mass on the right cheek, which exhibited rapid growth following trauma. Due to the suspicion of malignancy, an excisional biopsy with a 5 mm margin was performed, and histopathological examination revealed a proliferating pilomatrixoma. This case is noteworthy for presenting two variants: classification by size (giant pilomatrixoma) and histological subtype (proliferative). It is essential to ensure appropriate surgical management, as incomplete excision may lead to local recurrence and/or malignant transformation.

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