A Rare Occurrence of Ewing’s Sarcoma Presenting as Breast Mass: A Case Report and Literature Review

Abstract

Ewing’s sarcoma (EWS) typically involves the bony structures in adolescents and young adults. Extraskeletal sarcoma is a rare, aggressive, and malignant soft-tissue tumor with high recurrence rate. EWS of the breast is a rare entity with <1% cases reported in literature. A 55-year-old lady who complained of the gradual onset painless breast lump lasting for 1 year was referred to our institute in August 2021. Diagnostic ultrasound of bilateral breast identified a cystic lesion measuring 1.8 × 1.5 cm in lower inner quadrant of right breast. Diagnostic excisional biopsy of the right breast lump, which was conducted outside of the institute, showed malignant small round cell tumor. Post-excisional biopsy whole body 18-fluoro-deoxy-glucose positron emission tomography showed no residual uptake with no evidence of metastatic disease elsewhere. Immunohistochemistry work revealed positive expression of NKX2.2 and MIC2, which is consistent with the histopathological feature of EWS. Fluorescent in situ hybridization showed EWSR1 rearrangement, which is consistent with the diagnosis of EWS. The patient underwent a wide local excision of the right breast, followed by adjuvant chemotherapy consisting of 18 weekly vincristine/adriamycin D/cyclophosphamide regimen (vincristine, total dose of 2 mg; adriamycin D 100 mg; and cyclophosphamide 1.6 g). The patient was disease free after follow-up of 1 year. The rarity of primary breast EWS poses a diagnostic dilemma and hence the treatment. Local control with systemic therapy is the cornerstone of the treatment, in which breast conservation surgery is equivalent to mastectomy in patient with a good/average breast volume.