The American Journal of dermatopathology
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Case Reports
Acute mucocutaneous methotrexate toxicity associated with interface dermatitis and numerous eosinophils.
Acute mucocutaneous methotrexate toxicity is not classically associated with prominent tissue eosinophilia. We present a case of acute methotrexate toxicity associated with pancytopenia and mucocutaneous erosion with interface dermatitis and numerous eosinophils. A 79-year-old male, with a history of psoriasis vulgaris on methotrexate therapy, presented with blisters of the oral mucosa, groin, sacrum, and extremities after daily consumption of methotrexate. ⋯ Although these changes are most often superimposed on psoriatic plaques, they have been reported to occur on normal skin. Therefore, the differential diagnosis may include lichen planus, a lichenoid drug eruption, or a fixed drug eruption, and given the presence of mucosal ulceration, incipient pemphigus vulgaris or paraneoplastic pemphigus vulgaris. This case illustrates that acute mucocutaneous methotrexate toxicity may be associated with both interface dermatitis and numerous eosinophils.