Morphologic Spectrum of Lymphadenopathy in Drug Reaction With Eosinophilia and Systemic Symptoms Syndrome

Context.— Drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (DRESS) is a drug-induced, adverse T-cell–mediated hypersensitivity reaction that most often involves skin. The pathologic findings of DRESS-related lymphadenopathy have been described infrequently in the literature. Objective.— To present a case series of DRESS-related lymphadenopathy with an emphasis on the morphologic spectrum. Design.— We describe detailed clinical and pathologic findings along with the literature review. We focus on the differential diagnosis between DRESS lymphadenopathy and angioimmunoblastic T-cell lymphoma (AITL). Results.— There were 4 men and 1 woman with a mean age of 41 years (range, 23–59 years). One patient (20%) died. Three lymph node biopsy specimens showed a pattern reminiscent of AITL (AITL-like pattern) and 2 cases showed necrotizing lymphadenitis (Kikuchi-like pattern), associated with vasculitis in 1 case. The AITL-like morphology of DRESS-related lymphadenopathy may be difficult to distinguish from genuine AITL. The clinical information is important for differential diagnosis, including history of drug exposure, age, and the rarity or absence of AITL-associated manifestations such as hemolytic anemia and hypergammaglobulinemia. Molecular analysis of the T-cell receptor genes is helpful, typically revealing a polyclonal pattern in DRESS-related lymphadenopathy. Conclusions.— In the literature, 4 histologic patterns of DRESS lymphadenopathy have been described: reactive lymphoid hyperplasia, necrotizing lymphadenitis, Hodgkin lymphoma–like, and AITL-like. These patterns, particularly those that resemble lymphoma, highlight the importance of correct diagnosis to avoid unnecessary therapies.