Epithelioid Osteosarcoma

Comments:
Cytokeratin AE1/AE3 shows patchy immunoreactivity in the epithelioid cells (inset) so it is not helpful in distinguishing between carcinomas and epithelioid osteosarcomas. Note the typical osteoid matrix on the left. Image courtesy of: Dr. Bulent Celasun, Ankara, Turkey.