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JPTM > Ahead-of Print

doi: https://doi.org/10.4132/jptm.2019.07.22    [Epub ahead of print]
Primary Rhabdomyosarcoma of the Breast: Study of Three Cases at One Institution with a Review of Primary Breast Sarcomas
Junyoung Shin1, Hee Jeong Kim2, Dae-Yeon Kim3, Gyungyub Gong1, Kyung-Ja Cho1
1Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
2Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
3Department of Pediatric Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Corresponding Author: Kyung-Ja Cho ,Tel: +82-2-3010-4545, Fax: +82-2-472-7898, Email: kjc@amc.seoul.kr
Received: March 11, 2019;  Revised: July 11, 2019  Accepted: July 22, 2019.  Published online: August 2, 2019.

Primary breast sarcoma (PBS) is rare, comprising approximately 1% of breast malignancies. Rhabdomyosarcoma (RMS) accounts for an extremely small proportion of PBSs, often leading to delayed histologic confirmation.
On reviewing Asan Medical Center’s pathologic database between 2000-2018, 41 PBS cases were retrieved, including 3 cases of primary RMS of the breast. Their clinicopathological features were analyzed, and literature related to PBS and primary RMS of the breast was reviewed.
We identified 3 primary breast RMS cases from our institution database, comprising 7.3% of PBS: one case each of spindle cell/sclerosing RMS (ssRMS), alveolar RMS (aRMS), and embryonal RMS (eRMS). All cases involved adolescents or young adults (14, 16, and 25 years) who underwent mastectomy or radiotherapy and were confirmed using immunohistochemical testing for myogenin, desmin, and myogenic differentiation 1. The ssRMS patient experienced recurrence at the operation site 4 months post-surgery despite undergoing concurrent chemoradiotherapy. The aRMS patient had multiple metastases at diagnosis and showed FAX3-FOXO1 fusion transcripts; she died 22 months after the diagnosis. The eRMS patient had enlarged axillary lymph nodes; post-radiotherapy, the lesion recurred as multiple metastases to the bone and lung. She died 18 months post-diagnosis.
Our experience on RMS cases suggest that spindle cell or small round cell malignancy in breasts of young female should be suspected for the possibility of primary or secondary RMS. To our knowledge, this is the second report of primary breast ssRMS, it may help clinicians who encounter this rare disease in the future.
Key Words: Spindle cell rhabdomyosarcoma, sclerosing rhabdomyosarcoma, primary sarcoma of the breast