Image Description
Differential Diagnosis of Struma Ovarii: The clear/oxyphilic cells of struma ovarii can mimic morphology of clear cell ovarian carcinoma, Sertoli cell tumor, and steroid cell tumor. Features favoring struma ovarii include follicular architecture (which is readily recognizable in most cases) and intrafollicular colloid. An immunohistochemical panel of thyroglobulin, TTF-1, CK7, EMA, inhibin, and calretinin can help confirm the diagnosis. The thyroid tissue is immunoreactive for thyroglobulin, TTF-1, and PAX8. When struma ovarii is extensively cystic, it should be differentiated from serous or mucinous cystadenomas.
The image shows irrregularly-shaped thyroid follicles surrounded by copious collagenized stroma in a cyst wall from a case of struma ovarii.
About the Disease
Germ cell tumors (GCT) of the ovary originate from primordial germ cells and make up 30% of all primary ovarian neoplasms. More than 90% of ovarian GCT are mature cystic teratomas which are benign tumors. Remaining 5% are malignant. Malignant GCT make up 3% and 20% of all ovarian cancers in Western countries and Asian/African countries respectively. Patients with malignant GCT are usually between 15-30 yrs. of age. Tumors are large (average size 16 cm) and generally unilateral (except dysgerminomas; 10-20% cases are bilateral). Presenting symptoms are abdominal enlargement and pelvic pain. Serum hCG and AFP levels can give a clue to the diagnosis and are useful in monitoring postoperatively. The treatment consists of fertility-sparing surgery followed by combination chemotherapy. About 60-75% of patients present with Stage I disease which has a cure rate of almost 100%. About 25-30% have Stage III disease at diagnosis and the cure rate is around 75%. REFERENCES: 1. WHO Classification of Tumors. Female Genital Tumors. 5th Edition, 2020; IARC, Lyon, France. 2. Nucci MR, Parra-Herran C (2021). Gynecologic Pathology. 2nd Edition. Philadelphia, PA. Elsevier. 3. Goldblum, J. R. et al (2018). Rosai and Ackerman's Surgical Pathology - Eleventh Edition. Philadelphia, PA. Elsevier.