Pilomatricoma at an unusual site mimicking malignancy: a case report

Udita Anand, Department of Pathology, ESIC Hospital and PGIMSR, Basaidarapur, New Delhi, India Priyanka Munjal, Department of Pathology, ESIC Hospital and PGIMSR, Basaidarapur, New Delhi, India Bhavna Sharma, Department of Pathology, ESIC Hospital and PGIMSR, Basaidarapur, New Delhi, India

Pilomatricoma is a benign adnexal tumor of hair matrix origin, commonly found in the head and neck region. Bullous pilomatricoma is a rare variant that is frequently misdiagnosed. Occurrence at unusual sites, such as the trunk or back, is rare and may lead to diagnostic confusion. A 23-year-old male presented with a gradually increasing mass over the right lower back for 2 months. On local examination, it was a soft, mobile, tender, subcutaneous nodule with superficial blister formation measuring approximately 3 × 2.5 cm. Fine-needle aspiration cytology was suggestive of malignancy. Based on clinical and cytological suspicion, a wide local excision was performed. Histopathological examination revealed features consistent with pilomatricoma. Pilomatricoma at uncommon sites can mimic malignancy both clinically and cytologically. The bullous variant of pilomatricoma represents only about 2% of all reported pilomatricoma cases. Awareness of its varied presentation is essential to avoid overdiagnosis and overtreatment. Complete excision remains the treatment of choice with excellent prognosis.

Keywords: Pilomatricoma. Pilomatrixoma. Back mass. Adnexal tumor. Malignant mimic.