Proliferative struma ovarii: A rare case report

Abstract

Dermoid cyst is the most common ovarian neoplasm, comprising up to 25% or more of all ovarian tumors,
and contains various mature tissues derived from one or more of the embryonic germ layers, the ectoderm,
mesoderm, and endoderm but occasionally transform to malignant. Struma ovarii is defined as teratoma
containing predominantly thyroid tissue up to 50% of the cases. Stroma ovarii is a very unusual and rare type
of teratoma and has been demonstrated in 5%–20% of the cases and comprises 3% of ovarian teratomas.
For struma ovarii, patient age ranges between 6 and 74 years and most patients are in their reproductive
years. Struma ovarii is predominantly unilateral and associated with mature cystic teratoma, ascites, pleural
effusion, and rarely with a cystadenoma. Tumor is composed of mature thyroid tissue comprising varying
sizes of follicles lined by columnar or flattened epithelium. Sometimes, the follicles are markedly crowded,
but other criteria of malignancy are absent, and hence, these cases are reported as proliferative struma
ovarii. Proliferative struma ovarii has a good prognosis. Some benign cases are misdiagnosed as carcinoma
when serum CA-125 is highly raised. As there are no specific clinical, radiological, and serological markers
available for this rare tumor, these are diagnosed on histopathology.