Abstract
We present a case of iododerma in a 41-year-old woman with a medical history of Graves disease. She was recently prescribed potassium iodide for improved management of her hyperthyroidism. A day following potassium iodide therapy initiation, she developed acneiform rash, confluent erythematous nodules and bullae, initially on her face, gradually spreading to her chest, arms and thighs. Punch biopsies of the lesions revealed moderately spongiotic epidermis, a neutrophilic upper and mid-dermal infiltrate, admixed with numerous acellular haloed structures that resembled cryptococcal organisms. There was no eosinophilic cellular infiltrate and fibrinoid vascular necrosis was not identified. GMS and PAS-D stains performed, were negative for infectious organisms as well as fungal tissue cultures. The clinical presentation and histologic features favored a diagnosis of iododerma. This diagnosis was further solidified with attenuation of the patients skin lesions following initial steroid therapy and discontinuation of potassium iodide. Iododerma is a halogenoderma that occurs following exposure to iodine-based compounds such as contrast and potassium iodide. Though rare, iododerma has diverse clinical and histologic manifestations but most frequently presents as a neutrophilic dermatosis. The presence of haloed structures within a dermal neutrophilic infiltrate is exceptional and additional workup may be required to rule out a fungal infection.
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