Eruptive nevi in a patient with constitutional mismatch repair deficiency (CMMRD).

Biallelic mutations in the DNA mismatch repair genes MLH1, MSH2, MSH6, or PMS2 result in one of the most aggressive genetic cancer conditions, constitutional mismatch repair syndrome (CMMRD). We present a case of a 10-year-old boy with biallelic MSH6 mutation and systemic lupus erythematosus with eruptive melanocytic nevi after receiving chemotherapy for mediastinal T-cell lymphoblastic lymphoma.