Methimazole Induced Steven-Johnson Syndrome

Steven-Johnson syndrome (SJS) &Toxic Epidermal Necrolysis (TEN) are drug-associated hypersensitivity reactions that result in desquamation & necrosis of the epidermal skin. While the pathogenesis is incompletely understood, research suggests that drug reactions initiated by cytotoxic T-lymphocytes play a major role. Therefore, proper identification of the culprit drug is crucial for patient care as prompt withdrawal can improve the immediate prognosis of active SJS. We present a case of Methimazole (MMI) induced SJS.

Case Description:

44 Y F recently diagnosed with Hyperthyroidism & started on MMI Therapy ~ 1 month ago, presented to the hospital with generalized weakness, tachycardia & dysuria x 2 wks. Vitals significant for hypotension & tachycardia. On PE she had multiple macular lesions with crusting across the face, torso, & extremities which she adds that are present x 2-3 wks. Lab work showed leukopenia, anemia, elevated creatinine, & transaminitis. UA suggestive of UTI & pt was started on Abx therapy for sepsis secondary to UTI.

Over the next few days, pt’s lesion progressively worsened with extensive skin sloughing throughout her body. Due to a clinical concern for SJS, all medications were held including MMI & burn care team was consulted. Autoimmune panel with Fluorescent Antinuclear Antibody (FANA) staining pattern was ordered, which suggested a drug induced systemic lupus erythematosus pattern. Skin biopsy also performed & revealed ‘Scattered Dyskeratinocytes, Focal interface dermatitis & Dermal scattered extravasated red blood cells suggestive of a drug reaction’. A prednisone taper regimen was subsequently started. Desquamated skin regions were treated with bacitracin & Xeroform. Her condition gradually improved & she was safely discharged to follow up with wound care.

Discussion:

This case demonstrates a rare instance of SJS in a patient who was recently started on MMI. Although review of available literature found no cases in adults, a clinical study by Rivkees (2009) found three cases of methimazole-associated SJS among one hundred children with Grave’s disease. Furthermore, support can be drawn from the Algorithm for Assessment of Drug Causality for Toxic Epidermal Necrolysis (ALDEN) developed by Sassolas (2009), which aimed to evaluate the causality of medications in SJS & TEN. Within ALDEN’s parameters, factors that support our case include the pt endorsing a skin reaction within twenty-eight days of drug intake, no known previous exposure of the drug, & drug presence within the body up until hospitalization. Ultimately, it is imperative that physicians be aware of the adverse effects of prescribed medications especially when rare such as this case.