Immune thrombocytopenic purpura: A rare side effect in a patient treated with Imiquimod for lentigo maligna

Topical Imiquimod is increasingly used in the treatment of lentigo maligna (LM) for patients not suitable or willing for surgery. It acts as an immune response modifier and is recommended for use with caution in patients with autoimmune disorders. A review of the literature did not reveal any reported cases of Idiopathic Thrombocytopenic Purpura (ITP) with the use of Imiquimod so far. We report a case of a 55-year-old woman with a history of Addison's and Graves' disease who had been diagnosed with lentigo maligna on the right nasal ala. Within two days of commencing of topical Imiquimod treatment, she was admitted to the hospital with extensive cutaneous and mucosal bruising and treated as acute Idiopathic Throbocytopenic Purpura. Deranged platelets were reversed promptly with treatment and Imiquimod discontinued. We demonstrate that Idiopathic Throbocytopenic Purpura is a potential life-threatening side effect of Imiquimod treatment and patients who have autoimmune disorders are at increased risk of developing this side effect. We recommend that Imiquimod is contraindicated in patients with autoimmune disease. Here we describe the clinical presentation and review the relevant literature on Imiquimod treatment for lentigo maligna and its potential side effects.