Cytologic findings in two cases of dermoid cysts with malignant transformation.

While dermoid cysts are fairly commonly seen in the surgical pathology practice, rarely is the malignant transformation of dermoid cysts seen. Even rarer still is the cytopathologic report of this manifestation. In both of these case reports, the diagnosis of the malignant transformation of a dermoid cyst was made only after the initial cytologic diagnosis of malignancy had been reported and further investigation identified the source of the malignant cells. Unfortunately in both of these cases, the disease was detected at an advanced stage. To my knowledge and with a thorough literature search, the first case will be the first reported case of an adenocarcinoma in a dermoid cyst present in a Pap smear as the initial diagnosis. While the second case of malignant melanoma in a dermoid has been reported in ascitic fluid, such reports are rare.