Ovarian Fibroma : Microscopic Features

Sex cord-stromal tumors of the ovary are a heterogenous group of relatively rare neoplasms arising from hormone-producing cells of ovarian cortical stroma. They make up approximately 8% of all ovarian tumors and are the most common ovarian tumors with endocrine manifestations. WHO Classification subdivides them into 3 main categories based on the predominant cell types. Pure stromal tumors have a mesenchymal appearance and include: fibroma, cellular fibroma, thecoma, luteinized thecoma with sclerosing peritonitis, sclerosing stromal tumor, microcystic stromal tumor, signet-ring stromal tumor, Leydig cell tumor, steroid cell tumor, and fibrosarcoma.Pure sex cord tumors have an epithelioid appearance and include: adult granulosa cell tumor, juvenile granulosa cell tumor, Sertoli cell tumor, and sex cord tumor with annular tubules.Mixed sex cord-stromal tumors include Sertoli-Leydig cell tumor, sex cord-stromal tumor, NOS, and gynandroblastoma.The most common are tumors in fibroma-thecoma group (80-85%) followed by granulosa cell tumors (10-15%). The remainder are quite rare. Most of the clinically malignant tumors are granulosa cell tumors. References:1. Mutter G. L.& Prat J (2014). Pathology of the Female Reproductive Tract - 3rd Edition. Churchill Livingstone Elsevier.2. WHO Classification of Tumors. Female Genital Tumors. 5th Edition, 2020; IARC, Lyon, France.3. Nucci MR, Parra-Herran C (2021). Gynecologic Pathology. 2nd Edition. Philadelphia, PA. Elsevier.4. Goldblum, J. R. et al (2018). Rosai and Ackerman's Surgical Pathology - Eleventh Edition. Philadelphia, PA. Elsevier.