March 2023 – Gynecological Pathology

A 20-year-old woman with no significant past medical history presented with 14.5 cm ovarian mass. She underwent an oophorectomy. Grossly, the ovarian mass shows yellow to white, firm cut surface. Representative sections of the ovarian mass depicted below, along with the selected immunohistochemical stains.

Figure 1: Low-power image
Figure 2: High-power image
Figure 3: SF-1
Figure 4: TFE3 IHC
Figure 5: Keratin AE1AE3

What is your diagnosis?

  • Sclerosing stromal tumor
  • Microcystic stromal tumor
  • Fibrothecoma
  • Adult granulosa cell tumor

The correct answer is ...

Sclerosing stromal tumor.

Sclerosing stromal tumor are uncommon ovarian tumors that occur generally in young woman and girls with a mean age of 29 years. These tumors range in size from 1.5 cm to 19 cm. Gross examination, they are generally well circumscribed and have a yellow to white solid cut surface. They often show areas of central edema with cystic degeneration.

Microscopically, these tumors have pseudolobular appearance, with alternating hypocellular myxoid edematous areas and cellular areas with collagenized zones. They typically show abundant, thin-walled, dilated vessels with prominent branching, often with a hemangiopericytoma-like appearance. In the cellular areas, spindle-shaped cells and polygonal luteinized cells are present. The luteinized cells show eosinophilic to clear vacuolated cytoplasm, round nuclei, and prominent nucleoli. Occasionally the luteinized cells may have signet ring cell appearance, especially during pregnancy. Scant spindle cells with pale cytoplasm and elongated nuclei are also usually present. Mitotic activity is generally low.

Sclerosing stromal tumor are usually positive for sex cord markers, such as inhibin, calretinin, or SF1 but are negative for cytokeratin and EMA. Recent studies have shown that a subset of these cases shows TFE3 expression. 

The differential diagnosis includes other sex cord stromal tumors including fibrothecoma, microcystic stromal tumor, and adult granulosa cell tumor. Some tumors that demonstrate vacuolated cytoplasm may mimic metastatic signet ring adenocarcinoma. Fibrothecoma typically occur in peri- or postmenopausal woman with abnormal bleeding. Grossly the tumor demonstrates a uniform white cut surface. They typically lack the luteinized cells present in sclerosing stromal tumor and do not show the characteristic hemangiopericytoma like vasculature.

Microcystic stromal tumor is a benign ovarian tumor with striking microcystic growth. These tumors show admixture of microcysts, solid areas, and collagenous bands. They can often show bizarre nuclei in up to 60% of the cases. These tumors are usually very focally and weakly positive for inhibin and calretinin.

The adult granulosa cell tumor can show variety of growth patterns and should be considered in differential diagnosis for sclerosing stromal tumor. The adult granulosa cell tumor shows FOXL2 mutation in approximately 90% of the cases and can help in the diagnosis. Metastatic adenocarcinoma can be excluded by immunohistochemical studies (EMA positive and with specific epithelial markers such as CDX2, CK20, MOC31, as well as mucin stains).


  1. Park CK, Kim HS. Clinicopathological characteristics of ovarian sclerosing stromal tumor with an emphasis on TFE3 overexpression. Anticancer Res. 2017;37(10):5441-7.
  2. Al Harbi R, McNeish IA, El-Bahrawy M. Ovarian sex cord-stromal tumors: an update on clinical features, molecular changes, and management. Int J Gynecol Cancer. 2021;31(2):161-8.
  3. Atram M, Anshu, Sharma S, Gangane N. Sclerosing stromal tumor of the ovary. Obstet Gynecol Sci. 2014;57(5):405-8.

Raima Memon, M.B.B.S.

Fellow, Surgical Pathology
Mayo Clinic

Amy Clayton, M.D.

Consultant, Anatomic Pathology
Mayo Clinic
Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine and Science

MCL Education

This post was developed by our Education and Technical Publications Team.