osseous epithelioid sarcoma
Synopsis
partially calcified intraosseous lesion of the iliac bone
relatively uniform but clearly malignant-appearing epithelioid cells
scattered rhabdoid-appearing cells
hyalinized to partially calcified matrix
chickenwire" pattern of calcification
Immunohistochemistry
cytokeratins +
vimentin +
epithelial membrane antigen (EMA) +
CD34 +
complete loss of INI1 protein expression
Fluorescence in situ hybridization
possible homozygous deletion of the INI1 gene
Differential diagnosis
chondroblastoma
osteosarcoma
References
Primary Epithelioid Sarcoma of Bone: Report of a Unique Case, With Immunohistochemical and Fluorescent In Situ Hybridization Confirmation of INI1 Deletion. Raoux D, Péocʼh M, Pedeutour F, Vaunois B, Decouvelaere AV, Folpe AL. Am J Surg Pathol. 2009 Apr 1. PMID: #19342946#