Lenalidomide-induced symmetrical drug-related intertriginous and flexural exanthema.

Symmetric drug-related intertriginous and flexural exanthema (SDRIFE) is a cutaneous drug reaction that presents with symmetrical erythema in the flexures. The reaction typically appears hours-to-days after drug exposure but has been reported to occur months after drug initiation. Diagnostic criteria include cutaneous reaction after exposure to a systemic drug, erythema of the gluteal region and/or V-shaped erythema of the inguinal areas, involvement of an additional intertriginous site, symmetry, and absence of systemic involvement. The rash typically presents as macular erythema. However, variations in morphology have been reported including papules, pustules, vesicles, and bullae. The histopathology of SDRIFE is non-specific and the diagnosis is made clinically. Cessation of the causative drug leads to gradual rash resolution. Beta-lactam antibiotics are the most implicated medications but case reports describe SDRIFE following monoclonal antibodies, chemotherapeutic agents, and various other medications. We present a patient with SDRIFE secondary to lenalidomide, an immunomodulatory agent. This case highlights the importance of considering SDRIFE in the differential diagnosis of patients presenting with intertriginous erythema.