URTICARIAL PATHOLOGY IN SCHNITZLERS (HYPER-IGM) SYNDROME

Background: Schnitzler's syndrome is a rare disorder characterized by chronic urticaria and monoclonal ISM gammopathy. The mechanisms of the urticarial flares remain poorly understood. Objective: To more accura tely define the histopathologic changes in urticarial lesions, we revi ewed 25 original biopsies from 15 cases of Schnitzler's syndrome, 11 o f which have previously been reported. Results: Thirteen specimens fro m 9 patients showed urticaria with neutrophils (neutrophilic urticaria ). Necrotizing leukocytoclastic vasculitis with positive immunofluores cence studies was found only in 2 biopsies from 1 patient who was gene tically deficient in C4. Five specimens showed lymphocytic urticaria. Four biopsies demonstrated a spongiotic dermatitis; an eosinophilic sp ongiosis was seen in 2 biopsies from a patient who later developed pem phigus vulgaris. Epidermal changes were seen in 17 specimens from 10 p atients. Conclusions: The histopathologic findings in Schnitzler's syn drome are not uniform although most cases demonstrated neutrophilic ur ticaria. Neutrophils in Schnitzler's syndrome are not usually related to immune complex vasculitis. Epidermal changes in Schnitzler's syndro me need to be further analyzed.