Functional ovarian tumors of stromal and sex cord origin.

Most functional ovarian tumors are of specific stromal or sex cord origin, capable of differentiating in either a female direction or, less commonly, a male direction. Tumors of stromal origin such as thecoma, stromal luteoma, and Leydig cell tumors are for all practical purposes benign, and evolve from mature ovarian stroma, recapitulating common non-neoplastic transformations such as stromal changes associated with follicle development and nodular stromal hyperplasia. Sex cord tumors of granulosa or Sertoli cell types are generally of a low order of malignancy, tending to late recurrence, occasional peritoneal seeding, and only rarely to distant metastasis. Nonfunctional tumors of the ovary may trigger hormone production from adjacent reactive stroma. Massive edema of the ovary due to partial torsion may simulate neoplasm and may produce hormonal syndromes by an unknown mechanism.