Primary cutaneous biphasic sarcomatoid basal cell carcinoma with myoepithelial carcinoma differentiation: a new variant,
Claudia Mestre‐Alagarda  Gema Nieto  Liria Terrádez  Carlos Monteagudo
First published: 06 July 2019 https://doi.org/10.1111/cup.13543
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/cup.13543.
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ABSTRACT
Isolated cases of basal cell carcinoma with partial myoepithelial component have been described. However, myoepithelial differentiation has not been described in sarcomatoid basal cell carcinomas, which usually show osteosarcomatous, chondrosarcomatous or leiomyosarcoma‐like features. We report a case of an 87‐year‐old man with a forehead lesion that histologically showed a minor component of conventional nodular BCC in transition with a major biphasic sarcomatoid growth composed by invasive spindle‐cell and epithelial‐like components, the latter with a reticular pattern and scattered ductal structures. Both components showed cytological atypia and high mitotic rate (26/10HPF), with atypical mitoses. BER‐EP4 immunostaining was exclusively found in the nodular BCC component whereas the sarcomatoid component revealed immunostaining for α‐smooth muscle actin, muscle specific actin, calponin and p63 in both epithelial‐like and spindle cell populations. Focal immunoreactivity was observed in the epithelial component for S100 and GFAP. Furthermore, EWSR1‐PBX1 gene fusion was also detected. This is to our knowledge, the first fully documented case of biphasic sarcomatoid basal cell carcinoma with myoepithelial carcinoma differentiation.