Just an excuse to put up some cracking photographs of this case:
Struma ovarii fall into the highly specialised mature cystic teratoma group. These are teratomas that consist predominantly or exclusively of one type of adult tissue and also include carcinoid tumour, epidermoid cysts and neuroectodermal tumours.
This case showed a haemorrhagic thin walled cyst with thyroid tissue and areas showing hurtle cell change. No immature features were seen. There was no evidence of a malignant thyroid tumour which although very rare is worth looking for.
Robboy’s Pathology of the Female Reproductive Tract.