Drug-induced pseudolymphoma and hypersensitivity syndrome - Two different clinical entities

Objective: To test the hypothesis that drug-induced pseudolymphoma and hypersensitivity syndrome are 2 distinct clinical entities. Design: Retrospective study from 1980 to 1993. Setting: Departments of dermatology and medicine of 5 referral universitary hospitals. Patients: Twenty-four patients who met arbitrary criteria selected as being suggestive of lymphoma, with probable drug cause. Patients with other definite cutaneous drug-induced eruptions were excluded. Intervention: None. Main Outcome Measures: Suspect drugs; clinical, biological, and pathological findings; and evolution of each case and of 110 published case reports. Results: Two groups were separated according to their mode of onset and clinical aspect. Three patients (and 15 cases in the literature) had subacute papulonodular or infiltrated plaques, without visceral involvment. Skin biopsy specimens showed a dense lymphocytic infiltrate mimicking lymphoma. Healing was constant when the drug was stopped. The 21 remaining patients (and 95 published cases) had an acute widespread eruption, with fever, enlarged lymph nodes, and multivisceral involvement. Lymphocytosis, atypical lymphocytes, eosinophilia, hepatitis, and high levels of lactate dehydrogenase were frequent. Skin biopsy findings were usually not specific (lymphocytic infiltrate and keratinocyte necrosis) but sometimes mimicked lymphoma. Severe forms and relapses occurred, even after the drug was stopped. The inducing drugs were the same in the 2 groups. Conclusions: These 2 groups correspond to drug-induced pseudolymphoma and hypersensitivity syndrome. We think that they are 2 distinct entities with different clinical and biological features and outcome, even if the pathological findings are sometimes similar. Prospective studies are needed to confirm these facts, to evaluate the therapy, and to follow up patients.