An unusual calcifying tumor of the ovary occurring in a 23-year-old woman is described. The tumor did not produce any endocrine symptoms. Histologically, it was paucicellular and displayed extensive sclerotic stroma with numerous calcifications. The fibroblast-like cells were arranged in vague pseudolobules thus resembling overall the architecture of the sclerosing stromal tumor (SST), but the hemangiopericytoma-like vasculature typical of SST was not seen. However, immunohistochemical endothelial markers CD31 and CD34 showed a surprisingly high number of small vessels that were not apparent in hematoxylin-eosin stained sections. The tumor cells were positive for alpha-inhibin, CD99, actin, and negative for desmin, S100 protein, and epitehelial markers. This type of ovarian stromal tumor may represent a calcifying stage of SST.

        Key words: ovary - sclerosing stromal tumor - calcification - calcifying stromal tumor - inhibin