Pulmonary-type adenocarcinoma and signet ring mucinous adenocarcinoma arising in an ovarian dermoid cyst: report of a unique case.

Dermoid cysts are common benign ovarian germ cell neoplasms. Occasionally, one of the mature elements undergoes malignant transformation resulting in the formation of a somatic malignancy; most commonly this is squamous carcinoma. We report a unique case where 2 separate malignancies arose within a dermoid cyst, one a signet ring mucinous adenocarcinoma and the other a pulmonary-type adenocarcinoma. There have been only occasional earlier case reports of a possible pulmonary-type adenocarcinoma arising in a dermoid cyst. In the case we report, the pulmonary-type adenocarcinoma was closely associated with a bronchial structure and exhibited diffuse positive immunohistochemical staining with TTF1, PE10, and napsin A. Molecular studies revealed no evidence of epidermal growth factor receptor mutation, a molecular alteration which may be found in primary pulmonary adenocarcinoma.