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Case Reports in Pathology
Volume 2015 (2015), Article ID 406739, 5 pages
http://dx.doi.org/10.1155/2015/406739
Case Report

Adipocyte-Like Differentiation in a Posttreatment Embryonal Rhabdomyosarcoma

1Department of Pathology, University of California, San Francisco, 505 Parnassus, M580, San Francisco, CA 94143, USA
2Departments of Pathology and Dermatology, University of California, San Francisco, 1701 Divisadero Street, Suite 280, San Francisco, CA 94115, USA
3Department of Pathology, University of California, San Francisco, 1825 4th Street, M2354, San Francisco, CA 94143, USA

Received 17 September 2015; Revised 18 November 2015; Accepted 1 December 2015

Academic Editor: Khin Thway

Copyright © 2015 Dana Balitzer et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We describe a 16-year-old boy with rhabdomyosarcoma, consistent with embryonal subtype, of the lower extremity who received systemic neoadjuvant chemotherapy and subsequent excision. Microscopic sections of the postchemotherapy excision demonstrated diffuse, prominent, and immature adipocyte-like differentiation, in addition to skeletal muscle differentiation. Adipocyte-like differentiation was confirmed by a combination of positive Oil Red O and adipophilin immunohistochemical staining. To our knowledge, this represents the first report of an unusual phenomenon of differentiation of a soft tissue rhabdomyosarcoma into adipocyte-like cells after chemotherapy.