Differentiating Desquamating Skin Lesions: A Case of Methotrexate Epidermal Necrosis.

Desquamating skin lesions are a non-specific finding that requires urgent evaluation given the life-threatening severity of one of the potential causes, Stevens-Johnson syndrome (SJS). Methotrexate toxicity, also known in its cutaneous form as methotrexate epidermal necrosis (MEN), is another entity that presents similarly to SJS and is described here in a patient with increased risk due to his age, chronic kidney disease, and increased dose of methotrexate. His diagnosis was complicated by other historical risk factors, including antibiotic use, but was eventually elucidated when he was noted to have bone marrow suppression. Given the pathophysiology of SJS, a T-cell mediated reaction, the patient's leukopenia increased the likelihood of MEN as his ultimate diagnosis. However, in light of his aggressive treatment and non-specific histopathology, the clinical suspicion of MEN could not be confirmed.