Case Presentation: A 46-year-old female with a history of hypertension and end-stage renal disease presented with a progressive rash. Three days prior to presentation, she underwent a fistulogram using iodine contrast for evaluation of a non-functioning fistula. Several hours later she developed an irregular skin eruption over her legs, subsequently developing lesions involving the torso, upper extremities and oral mucosa. Lesions were pruritic and painful. She denied difficulty breathing, throat swelling, nausea/vomiting, and fevers. Vital signs were normal except for mild tachycardia with heart rate of 105 beats per minute. Examination of the skin revealed skin lesions in multiple stages distributed over the arms, legs, torso, and face. Newer lesions consisted of erythematous umbilicated papules (figure 1) and older lesions appeared as hemorrhagic and vesiculated plaques (figure 2). Initial lab work was notable for mild leukocytosis (15.0 K/ul) and elevated ESR (85 mm/h). A biopsy was performed revealing a neutrophilic infiltrate along with structures within halos suggestive of fungal infection. Fungal stains were negative. An extensive infectious workup including testing for HIV, syphilis, hepatitis, histoplasmosis, blastomycosis, coccidioides, cryptococcus, and blood fungal assays were negative. With a negative infectious workup and recent contrast exposure, iododerma was added to the differential. On day 6 from symptom onset, serum iodine level was elevated to 47,459mcg/L (normal 52-109mcg/L) and random urine iodine was 344,988 mcg/L (normal 34-523mcg/L). A diagnosis of iododerma was made. The patient was treated with topical steroids. The rash initially worsened during the first week, but subsequently showed marked improvement at two weeks, and near resolution at two months.
Discussion: Iododerma is a rare skin eruption associated with iodine exposure. It can develop after exposure to intravenous radiocontrast as well as iodide from oral medications and topical preparations. The pathophysiology of the condition remains poorly understood. Two case reports of iododerma from the 1970s included testing for iodide hypersensitivity with intradermal skin tests and lymphocyte transformation tests, but both studies failed to confirm that this was the underlying mechanism. Almost all patients with iododerma are noted to have renal dysfunction. The rash has been characterized as acneiform, pustular, hemorrhagic, bullous, and nodular and its heterogeneity adds further complexity to making the diagnosis. Classically diagnoses of iododerma have been based on history, presence of rash and elevated iodine levels. Biopsies have generally shown a neutrophilic dermatosis with haloed structures similar to that of Cryptococcus. Treatment is based on expert opinion and consists of topical or oral steroids, as well as hemodialysis if indicated. Overall prognosis for this condition is good; the most common adverse outcome is scarring.
Conclusions: Iododerma is a rare skin eruption that can have a very heterogenous presentation following exposure to iodine containing compounds. It is important for the hospitalist to include iododerma in their differential to facilitate earlier diagnosis and avoid un-necessary testing and antimicrobial exposures in the appropriate clinical setting.
