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.