18 August 2010 – Case of the Week #184
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Case of the Week #184
A 37 year old woman complained of lower abdominal pain. An abdominal ultrasound revealed a right ovarian solid mass, which was excised. The ovoid mass measured 5 x 4 cm and had a glistening smooth outer surface. The cut section was yellowish with areas of hemorrhage.
The tumor cells were immunoreactive only for Vimentin (see above), and negative for cytokeratin, EMA, AFP and chromogranin. The vacuoles were negative for PAS, Alcian blue and Sudan III.
What is your diagnosis?
Ovarian signet-ring stromal tumor
Ovarian signet-ring stromal tumor, first described in 1976 (Cancer 1976;38:166, free full text), is a very rare tumor, with less than 20 cases reported to date.
Histologically, it is composed of spindle and round cells, which contain a large cytoplasmic vacuole which displaces the nucleus, resembling a signet-ring. Numerous cells may show intracytoplasmic hyaline globules, which may actually be degenerating erythrocytes phagocytosed by the tumor cells (Ultrastruct Pathol 1995;19:401). The tumor cells are immunoreactive for vimentin, actin, inhibin and calretinin. They are negative for keratins, mucin and lipid stains.
Ovarian signet-ring stromal tumors are classified in the Thecoma-Fibroma category of ovarian tumors. They may be related to ovarian sclerosing stromal tumor (Pathol Res Pract 2010;206:338).
The differential diagnosis includes other signet-ring tumors, including Krukenberg tumor, primary or metastatic mucinous carcinoma of the ovary, mucinous carcinoid tumor and clear cell carcinoma. All of these tumors have some epithelial component that is immunoreactive with keratin. Krukenberg tumors are often bilateral or associated with extraovarian tumor. The signet-ring cells are immunoreactive for keratin and PAS-diastase, and negative for vimentin (Int J Gynecol Pathol 2004;23:45).
Ovarian signet ring stromal tumor has benign behavior, and excision is curative.
Nat Pernick, M.D., President
and Liz Parker, B.A., Associate Medical Editor
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