Signet-ring chondrosarcoma: a new morphologic entity

A 65-year-old, otherwise healthy white man presenting with an asymptomatic anterior chest wall mass diagnosed from a routine preoperative chest x-ray is reported. A fine needle aspirate of the mass was initially interpreted as a metastatic adenocarcinoma with prominent "signet-ring" features, but ultrastructural study of the cell block later suggested a chondrosarcoma. The resected surgical specimen confirmed the diagnosis of a grade 2 chondrosarcoma, with most of the tumor cells containing a large, clear, single vacuole shown to be lipid. The positive immunostaining for vimentin and S-100 as well as the ultrastructural appearance confirmed the diagnosis of a chondrosarcoma. Flow cytometric DNA analysis of the tumor on two separate occasions documented a very large aneuploid cell population (50% to 60%) which, when interpreted with the histologic appearance, suggested an aggressive tumor. This case illustrates the first published example of a "signet-ring" chondrosarcoma.