Hodgkinoid histiocytosis, a distinctive histiocytic/dendritic cell disorder clinically mimicking drug-induced hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms.

We report a case of Hodgkinoid histiocytosis (HH) with protracted skin manifestations. A 72-year-old Japanese woman presented with fever of unknown origin, lymphadenopathy, eosinophilia, and a generalized pruritic and erythematous maculopapular rash. Biopsy of an inguinal lymph node indicated a proliferation of large cells with clear cytoplasm, mimicking Hodgkin lymphoma (HL). Immunohistochemical analysis showed that the Hodgkin-like cells were positive for S-100 protein and CD30 but negative for langerin, CD20, PAX5, and CD3. The cells were also positive for PD-L1. The histological findings were similar to those of HL; conversely, immunohistochemical results suggested a histiocytic/dendritic cell origin. Therefore, the patient was diagnosed with HH. Systemic corticosteroid therapy markedly improved her systemic manifestations; nonetheless, cutaneous symptoms persisted. Drug-induced hypersensitivity syndrome (DIHS)/drug reaction with eosinophilia and systemic symptoms (DRESS) was suspected because of the prolonged cutaneous manifestations, and the diagnostic criteria for these conditions were fulfilled. Discontinuation of the culprit drug resulted in the remission of cutaneous symptoms. Because lymph node lesions in DIHS/DRESS also demonstrate HL-like histology, this case suggests that HH, while a novel and distinct histiocytic/dendritic cell disorder, may be associated with lymph nodal lesions occurring in the context of DIHS/DRESS.