Use of topical povidone-iodine resulting in an iododerma-like eruption

Iododerma is a rare skin eruption that is usually induced by the systemic use of iodide-containing radiographic contrast medium or treatment with oral potassium iodide therapy. Iododerma has also rarely been reported to occur following topical application of iodine. We herein report the case of a 42-year-old male who developed multiple pinpoint pustules on both lower extremities. Three days after the eruption began, the patient started applying topical 10% povidone-iodine solution to the lesions. During this treatment, the lesions enlarged into multiple 2-9-cm pus-filled bullae, limited to the treated areas. Lesional bacterial culture swab and Gram stain were negative. Blood cultures were also negative and the patient's white blood cell count was normal. A punch biopsy specimen revealed pseudoepitheliomatous hyperplasia and dermal-epidermal separation with epidermal necrosis and underlying abscess formation. A superficial and deep perivascular, interstitial and perifollicular infiltrate containing numerous neutrophils, with abscess formation and eosinophils was also seen. This histology was consistent with iododerma and the patient's lesions involuted following cessation of topical iodine use, leaving only post-inflammatory hyperpigmentation. In summary, our patient likely had a folliculitis that was then treated with topical povidone-iodine that led to iododerma. Although it remains possible that the reaction was an unusual contact hypersensitivity response, the ulceration, pseudoepitheliomatous hyperplasia and abscess formation do support an iododerma-like eruption.