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Internal malignancy, loss of MMR protein expression associated with sebaceous neoplasms

The high internal malignancy rates of patients with sebaceous neoplasms may explain their loss of mismatch repair protein expression, according to study results.

Researchers determined the frequency of visceral tumors and measured the mismatch repair (MMR) protein expression status in 85 patients with sebaceous neoplasms. Skin samples were taken from each patient and categorized as a sebaceous adenoma (n=45), a sebaceoma (n=15), or a sebaceous carcinoma (n=17). Immunohistochemistry (IHC) testing examined MMR protein expression rates for each participant.

Study results showed 22 visceral malignancies among 19 patients, including 17 patients with tissue samples or blood available. Ten of these patients (59%) with visceral malignancy also had loss of MMR protein expression by IHC or an indication of MMR gene mutation.

“Our findings demonstrate an increased frequency of internal malignancy in patients with sebaceous neoplasms compared with the general population, and highlight the heterogeneous nature of the visceral tumors,” the researchers concluded. “A majority of the sebaceous tumors show loss of MMR expression. The study reminds us to strive toward a consistent and comprehensive approach to screening for internal malignancy when a patient is given a diagnosis of a sebaceous neoplasm.”