Ovarian teratomas with florid benign vascular proliferation: a distinctive finding associated with the neural component of teratomas that may be confused with a vascular neoplasm.

Prominent benign vascular proliferations associated with neural tissue in five cases of ovarian teratoma are described. The ages of the patients ranged from 15 to 35 years. Three of the five had tumors confined to the ovary, one had peritoneal implants, and one had widespread metastatic immature teratoma. Two of the patients are alive and well, 8 and 9 years postoperatively. Follow-up is unavailable in two cases and the final case was recent. The tumor in three of the cases had features of mature cystic teratoma including abundant mature neural tissue and, in one instance, microscopic foci of primitive neuroepithelium. The tumor in the fourth case was an immature teratoma with abundant primitive neuroepithelium, and in the fifth case was a mixed germ cell tumor, composed mostly of immature teratoma with a minor component of yolk sac tumor. In all the tumors there was a prominent vascular proliferation composed of long thin-walled, curved vessels or a solid glomeruloid arrangement. Immunohistochemistry done in two cases confirmed the vascular nature of the proliferation. Angiogenesis, likely as an expression of vascular endothelial growth factors, is a well-known phenomenon in a variety of neural and neuroendocrine neoplasms, in particular high-grade gliomas. However, very few cases of this phenomenon have been described in association with neural tissue in the ovary. Recognition of this proliferation as a benign secondary one is important to avoid misdiagnosis of a vascular neoplasm or an immature teratoma, as happened in one of our cases.