Pilomatricoma: case report and review of the literature

Introduction

The etiology of a calcifying epithelioma might be due to a mutation in the CTNNB1 gene. This gene codes for the beta-catenin protein and it plays a role in cell-cell adhesion at the cell membrane and signal transduction in the nucleus. This lesion was first described by Malharbe and Chenantais in 1880. It was renamed from calcifying epithelioma to pilomatricoma when the etiology was identified to arise from hair follicle matrix. Dermatological lesions are more common in children and young adults and more prevalent in the first decade of life. The most frequent location is the head and neck region. It usually manifests as a firm subcutaneous nodule of skin.

Materials and Methods

A 22-year-old female with no remarkable medical history presented with a 3-year history of well-demarcated, firm entity in the right preauricular region. The overlying skin was erythematous and exfoliating on exam. The entity was 3 cm x 2.5 cm. CT with contrast revealed a well-circumscribed oval-shaped 3.9 × 1.6 × 3.6 cm subcutaneous soft tissue tumor with densely packed punctate calcifications are seen involving the right temporal region anterior to the auricle. Clinical differential diagnosis included sialocele, lymphoepithelial cyst, and pleomorphic adenoma. Following the CT scan with contrast, the differential diagnosis was modified to a dermoid cyst, epidermoid cyst, and pilomatricoma due to superficial, subcutaneous nature of the pathology. An incisional biopsy was conducted under local anesthesia using a preauricular approach. Gross examination revealed a reddish brown with gritty hard tissue fragments.

Results

Based on the histopathological interpretation, the entity was diagnosed as a pilomatricoma. Conclusion: Pilomatricoma is an uncommon entity found in the head and neck region. Practitioners should be familiar with it and include in their differential diagnosis of cutaneous dermatopathology.