Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS) Syndrome With Predominant Renal Involvement and Cholestatic Liver Injury: A Case Report.

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is a rare but potentially life-threatening drug-induced hypersensitivity reaction characterized by delayed onset and variable multi-organ involvement, which can complicate timely diagnosis. We report the case of a 75-year-old female who developed fever, generalized pruritic maculopapular rash, facial edema, lymphadenopathy, and acute kidney injury 10 days after completing a one-week course of amoxicillin-clavulanate for a respiratory infection. Laboratory evaluation revealed leukocytosis with neutrophilia, mild eosinophilia not meeting diagnostic threshold criteria, acute kidney injury with proteinuria and hematuria, and isolated cholestatic liver injury without significant ALT or AST elevation; atypical lymphocytosis was absent. Autoimmune serology and viral hepatitis screening were negative. Based on the RegiSCAR scoring system, the patient achieved a score of 7, consistent with a definite diagnosis of DRESS. Systemic corticosteroid therapy, alongside adjunctive topical treatment and antihistamines, led to progressive clinical and laboratory improvement. This case represents an atypical presentation of DRESS with predominantly renal involvement and isolated cholestatic liver injury, where the absence of typical hematologic manifestations posed a diagnostic challenge. Although viral reactivation, particularly HHV-6, is often implicated in DRESS pathogenesis, its role here remains unconfirmed due to the lack of virological testing. The case highlights the importance of considering DRESS in patients with delayed-onset cutaneous eruptions and unexplained acute kidney injury after drug exposure, even in the absence of classic hematologic features, as early recognition and appropriate management are crucial for favorable outcomes.