Isolated granulocytic sarcoma of the ovary: histologic, electron microscopic, and immunohistochemical findings.

An isolated granulocytic sarcoma (myelosarcoma) of the right ovary occurred in the absence of leukemia in a 49-year-old woman. The diagnosis of this tumor, which occurs extremely rarely in the ovary, was established by light microscopic, immunohistochemical, and electron microscopic investigations. The major cell population consisted of immature myeloid cells; scattered megakaryocytes were also seen. The tumor exhibited a prominent cellular stroma with scattered follicle-like collections of B-lymphocytes and many fibroblasts, giving the initial impression that the tumor could be of mesenchymal origin. Twelve months after operation, the patient still exhibits no evidence of leukemia.