Cutaneous Ciliated Cysts: 2 Case Reports and Review of Literature.

Cutaneous ciliated cysts are rare benign lesions most commonly seen in the lower extremities of young female patients. There is still ongoing debate about the origin of these cysts, with the most common theories being Mullerian heterotopia and eccrine gland metaplasia. To further increase the data pool, we present 2 new cutaneous ciliated cyst cases and gathered data about all 67 cases of literature. We want to highlight that immunohistochemistry and demographic information may play a key role in distinguishing between the 2 possible origins of this cyst, namely estrogen receptor, progesterone receptor, and carcinoembryonic antigen immunohistochemistry. Estrogen receptor and progesterone receptor nuclear positivity is proof of Mullerian origin, but when they are negative with a positive carcinoembryonic antigen, the most likely origin is eccrine gland metaplasia. We advocate using the terms "Cutaneous Mullerian Cyst" and "Ciliated Cutaneous Eccrine Cyst" instead of "Cutaneous Ciliated Cyst" to accurately indicate their distinct origins.