Primary de novo malignant peripheral nerve sheath tumor of the breast mimicking mastitis. Report of a case and review of the literature.

Malignant peripheral nerve sheath tumor (MPNST) is a rare tumor representing <0.1% of malignant breast tumors. Here, we report a case of sporadic MPNST of the breast in a 45-year-old woman with a fast-evolving painful mass in the right breast associated with edema, redness, and increased local temperature, simulating mastitis. This presentation has not been reported. A review of the literature since 1992 has revealed 15 MPNST cases, including the present one with sufficient data for analysis. All the cases were women. The ages ranged from 16-60 years (mean 40.5 years). Duration of symptoms varied from four days to 15 years (mean 2.7 years). Tumor size ranged from 2.5-30 cm (mean 10.9 cm). 64.3% of tumors were well-circumscribed. Tumors were graded as grade 1 (7.7%), grade 2 (38.5%), and grade 3 (53.8%). Three (20%) cases showed histopathological peculiarities. Simple mastectomy was performed in four (26.7%) cases, radical mastectomy in six (40%) cases, and simple excision in five (33.3%) cases. There were no metastases in the six cases where axillary dissection was performed. Seven (53.8%) patients received adjuvant therapy, including chemotherapy and∕or radiotherapy. Local recurrence was observed in two (16.7%) patients. Distant metastasis was detected in one patient (7.7%) affecting the lung 11 months after radical mastectomy. The follow-up was available for 10 patients (mean 2.2 years, median 1 year). One patient (10%) died of the disease. At the last follow-up, 80% of patients were still alive. The main differential diagnosis includes nonpleomorphic spindle cell tumors.