Published online Oct 6, 2020. doi: 10.12998/wjcc.v8.i19.4466
Peer-review started: May 24, 2020
First decision: July 25, 2020
Revised: July 28, 2020
Accepted: September 4, 2020
Article in press: September 4, 2020
Published online: October 6, 2020
Processing time: 126 Days and 5.4 Hours
Rhabdomyosarcoma (RMS) of the breast, a mesenchymal neoplasm with skeletal muscle differentiation, is an extremely rare tumour in males, with less than 30 cases published in English-language literature. We report on the first case of a male breast RMS, with an unusual ectomesenchymal/neuroectodermal component.
A 55-year-old, previously healthy male, underwent a radical left mastectomy for an ulcerated tumour mass, occupying the breast and left anterior thoracic wall. The biopsy specimen indicated the presence of a tumour with neural origins, namely a peripheral neuroectodermal tumour (PNET). The surgical specimens identified two components. The rhabdomyosarcomatous component (over 70%) was represented by large pleomorphic cells with positivity for desmin, sarcomeric actin and myogenin. The PNET-like ectomesenchymal component, which was admixed with the RMS cells, and was also revealed during the preoperative biopsy, consisted of small cells which expressed neurofilament, neuron specific enolase and CD99. The microscopic examination, along with the immunohistochemical profile, allowed the diagnosis of an RMS, with unusual ectomesenchymal differentiation. The patient refused the postoperative oncologic therapy and died three months after surgery.
In patients with RMS of the breast, the PNET-like ectomesenchymal component increases the diagnosis difficulty, especially in biopsy specimens. This differentiation can be immunohistochemically proven and might highlight the possible development of high-grade sarcoma of the breast from remnants of the embryological ectodermal layer.
Core Tip: In this paper we presented an exceedingly rare and aggressive case of mammary rhabdomyosarcoma (RMS) in a male patient. We found no cases previously published in international journals, reporting an RMS with a peripheral neuroectodermal tumour-like ectomesenchymal component, namely neuroectodermal differentiation. The specific nature of the case was indicated by the presence of the ectomesenchymal component in the biopsy specimen, the case being firstly diagnosed as a tumour with neural differentiation. These findings emphasize the need for an attentive microscopic evaluation of mesenchymal tumours in the mammary region, to further confirm or infirm the presence of a second highly-malignant tumour population.