Exfoliative Erythroderma Revealing Primary Central Nervous System Diffuse Large B-Cell Lymphoma.

Exfoliative erythroderma is a severe inflammatory skin condition that may result from pre-existing dermatoses, medications, or underlying malignancy. Although malignancy-associated cases are uncommon, persistent and treatment-resistant erythroderma should raise concern for an occult cancer. We report the case of an 82-year-old man with a one-year history of diffuse pruritic erythema and scaling involving nearly the entire body surface area that remained refractory to multiple dermatologic and immunosuppressive therapies. Initial evaluation for cutaneous lymphoma and systemic malignancy was negative. Months later, the patient developed a generalized seizure, and a brain MRI revealed a right frontal lobe mass. Biopsy later confirmed Epstein-Barr virus-positive primary central nervous system diffuse large B-cell lymphoma. This case highlights persistent exfoliative erythroderma as a potential paraneoplastic manifestation of an underlying malignancy and emphasizes the importance of continued evaluation for occult cancer when erythroderma remains unexplained and refractory to treatment.