Cytologic differentiation of struma ovarii from other ovarian neoplasms

To present the cytologic findings of struma ovarii and value of cytology and immunocytochemistry (ICC) using thyroglobulin (TGB) and thyroid transcription factor-1 (TTF-1) in evaluation of this unusual ovarian neoplasm, together with the diagnostic pitfalls.

Intraoperative cytologic findings of 7 patients with struma ovarii are reviewed. Cytologic material of both cystic and solid components was collected intraoperatively. ICC staining was done, and cell block preparation performed on selected cases.

The cases were divided in to 3 groups: group 1--diagnosis of struma ovarii was made by cytology and confirmed by ICC (1 case); group 2--diagnosis was suggestive on cytology or cell block and confirmed by ICC staining (4 cases); group 3--on cytologic diagnosis indistinguishable from other cystic ovarian neoplasms (2 cases). Cytologic findings were typically colloid with mosaic pattern, follicles, follicular cells only, sheets of follicular cells, both colloid and follicular cells, proteinaceous background or degenerated epithelial cells indistinguishable from other cystic ovarian neoplasms.

Cytologic findings of struma ovarii are distinct enough to be suggested intraoperatively, and ICC for TGB or TTF-1 is a valuable tool for preoperative fine needle aspiration biopsy and intraoperative diagnosis of this benign ovarian neoplasm.