Autosensitization Triggered by Neosporin Use: A Unique Phenomenon.

Interface dermatitis is a type of dermatological insult to the dermo-epidermal skin junction. When this reaction causes secondary dermatosis that occurs distally on the body, it is known as autosensitization or autoeczematization. Here, we present the case of a middle-aged gentleman, with a medical history including human immunodeficiency virus, non-adherent to highly active antiretroviral therapy, initially presenting due to chronic recurring cellulitis on the left lower leg that had become progressively erythematous and tender to palpation. A few days later, he developed an intensely pruritic, papular rash on his face and chest. Following further investigation, he reported using Neosporin ointment on the leg rash prior to admission which had then caused allergic contact dermatitis. Ultimately, the patient was diagnosed with acute interface dermatitis due to Neosporin use, which led to a secondary autosensitization reaction involving his head, neck, and arms. This case illustrates the importance of thorough history taking and clinical suspicion to appropriately diagnose this phenomenon, further demonstrating the temporal association between allergic contact dermatitis and autosensitization.