Sudden onset of Multiple nevi after administration of 6-mercaptopurine in an adult with Crohn's disease: a case report.

The correlation between combined chemotherapy, including 6-mercaptopurine, and development of excessive number of melanocytic nevi in childhood has been previously reported and studied. As of yet, no such relation has been reported in adults. We recently observed a 27-year-old female patient who developed numerous benign melanocytic nevi during a 20-month period while taking 6-mercaptopurine for Crohn's disease. The appearance of many nevi was worrisome to the patient from a cosmetic and medical perspective (given the higher risk of melanoma associated with large numbers of nevi).