[Struma ovarii and strumal carcinoid]

Seven ovarian tumours (3 mature teratomas, 2 strumas with malignancy 2 strumal carcinoids) have been examined histologically, hystochemically and electron-microscopically. It is shown that the cell composition of the strumal teratoma tissue is very similar to that of the ectopic thyroid. The follicular cells may proliferate either into the benign tumour (apudoma) or typical thyroid carcinoma. Parafollicular cells may give rise to C-cell hyperplasia with the amyloid deposits in the stroma. The so-called strumal carcinoid of the ovary represents probably the C-cell tumour. Its "strumal" component may be considered as preexisting follicles invaded by tumour apudocytes or as the site of tumour origin displaying the pattern of a non-medullary thyroid apudoma.