Abstract
Due to similar clinical and histopathologic appearances, erythema multiforme major (EMM), Mycoplasma pneumoniae-induced rash and mucositis (MIRM) and Stevens-Johnson syndrome (SJS) exist along an overlapping spectrum of mucocutaneous disease. A 34-year-old woman presented with two-week history of cough, three days of mouth sores and red eyes, and two days of a rash. There was no prior HSV. Lamotrigine was increased three weeks prior. On exam, she had conjunctival injection and crusted erosions of the gingival, buccal, and labial mucosa. Erosion was present on the labia majora. Atypical targetoid to vesicular papules were located on the chest and extremities. Nikolsky sign was negative. Lab studies showed leukocytosis. Chest XR was unremarkable. EMM, MIRM, and SJS were considered. Treatment was initiated with oral prednisone, doxycycline, and valacyclovir. Lamotrigine was held. After discharge, studies revealed rhinovirus/enterovirus by PCR. HSV1/HSV2 PCR were negative. Mycoplasma IgM was negative. Biopsy showed interface dermatitis with full thickness epidermal necrosis and moderate perivascular inflammation. It has been argued that due to divergent management and prognosis, diseases along the EMM/MIRM/SJS spectrum should be distinguished by etiologies of HSV, M. pneumoniae, and medications respectively. Some claim that that morphology can discriminate with EMM presenting with classic target acral lesions, MIRM with limited cutaneous disease with atypical targetoid acral lesions, and SJS with centrally distributed, extensive cutaneous disease. Retrospective histologic reviews found EMM has denser inflammation and less epidermal necrosis than SJS. However, there was no correlation between eosinophils and drug history or infection. Although some cases allow early distinction between these entities, in cases such as this, patients along the EMM/MIRM/SJS are best treated with a broad empiric approach, which can be narrowed depending on course and lab findings.
Financial Disclosure:
No current or relevant financial relationships exist.
