An unusual presentation of giant pilomatrixoma in an adult patient.

Background: Pilomatrixoma (OMIM ID #132600) is a benign cutaneous tumor originating from the pilosebaceous follicle and characterized by the presence of subcutaneous nodules of up to 3.0 cm in diameter, usually on the head, neck and upper extremities. It is most common in the first two decades of life and after the age of 60.

Main Observations: An adult female patient was evaluated, presenting a solid tumoral lesion with erythematous surface and purplish tone, with approximately 7.5 x 5.0 cm in size, in the interscapulovertebral region. It was thought to be an epidermoid cyst, sarcoma, calcified hemangioma, giant dermatofibroma, or nodular basal cell carcinoma. The resection of the lesion was carried out and, at the histological examination, specific details were observed that led to the diagnosis of pilomatrixoma.

Conclusion: Pilomatrixoma should be suspected in the differential diagnosis of giant adnexal tumors.