Primary Malignant Peripheral Nerve Sheath Tumor of the Breast: A Rare Case Report

Abstract

Abstract Introduction/Objective Primary breast sarcomas are uncommon and primary mammary malignant peripheral nerve sheet tumors (MPNST) are exceptionally rare. MPNST’s are malignant variants of peripheral nerve sheath tumors. These neoplasms are often associated neurofibromatosis type I (NF-I) but can also occur sporadically. They tend to occur in the deeper soft tissues, trunk, and extremities. Methods/Case Report A 60-year-old female was referred to our University Hospital for evaluation of an abnormal mammogram. Patient noticed a mass in the left breast 3 months ago and mammogram showed a large solid mass located at the left superior breast. Subsequent biopsy of the left breast lesion showed high grade malignant neoplasm with differential diagnosis of malignant phyllodes tumor, primary sarcoma, and metaplastic carcinoma. The tumor was non-responsive to the initial neoadjuvant therapy. The patient underwent modified radical mastectomy. The excised tumor was well-circumscribed, tan-white, firm, measuring 9.6 x 6.1 x 4.3 cm. The neoplastic cells were positive for CD99, S-100, SOX-10, neuron specific enolase, p53, Vimentin, focally positive for neurofilament, D2-40, p63, and negative for epithelial, melanoma and other sarcoma markers. The tumor was triple negative ER, PR, HER-2, with Ki- 67 at 61%. A diagnosis of primary high grade malignant peripheral nerve sheath tumor of the breast was rendered. The patient does not have a history of NF-1. There was no lympho-vascular or perineural invasion. After the surgery, the patient followed up without complications. Results (if a Case Study enter NA) N/A Conclusion An accurate diagnosis of this rare entity is necessary because it plays a crucial role in the therapeutic options and prognosis. In our case the patient was treated with neo-adjuvant chemotherapy followed by modified radical mastectomy. The purpose of presenting this unique case is to provide awareness of the existence of this entity among pathologists and clinicians for better patient care.