Pilomatrix Carcinoma Masquerading as Breast Carcinoma.

Pilomatrix carcinoma is an exceedingly rare skin adnexal neoplasm derived from piliferous follicles, usually occurring in the head and neck region. Localization of this tumor in the breast is a rarity. We now report an unusual case of a 49-year-old female who presented with a palpable mass in the left breast for 2 years. Mammogram revealed a large, lobulated opacity with calcification, and positron emission tomography-computed tomography showed a metabolically active soft tissue mass measuring 15 cm involving all the quadrants of the left breast. Subsequently, the patient underwent radical mastectomy, and histopathologic diagnosis of pilomatrix carcinoma of the breast was offered. Pilomatrix carcinoma, although exceedingly rare, can have an intramammary location and can be misdiagnosed as breast carcinoma on limited material. A high index of suspicion is required to arrive at an accurate diagnosis so as to obviate neoadjuvant chemotherapy.