Primary primitive neuroectodermal tumor of the breast: a rare case presentation.

A primitive neuroectodermal tumor (PNET) in the breast developed in a 36-year-old Indian woman who initially underwent lumpectomy and was diagnosed as the malignant phyllodes tumor of the right breast. Within 2 months it recurred, clinicoradiologically appearing like organized collection. Incision and drainage along with biopsy was done. The tissue diagnosis was reported as PNET. The histopathology report showed the tumor cells as malignant round cells, immunohistochemically positive for CD99, vimentin and neuron-specific enolase (NSE) (patchy) and negative for CD45, cytokeratin, S100, and desmin. Extended simple mastectomy was carried out. She came after another interval with recurrence. Chemotherapy as well as radiotherapy was given. After 18 months of surgery, the patient is having persistent stable disease without distant metastasis. PNET in adults is rare and has been reported in the chest wall (Askin tumor) and other visceral sites. To our knowledge, only a few cases have been reported of a primary PNET of the breast.