[Cutaneo-systemic necrotizing vasculitis occurring during desensitization].

Abstract

The authors report a case of cutaneo-systemic necrotizing vasculitis, predominantly affecting the skin and digestive tract, observed in an asthmatic patient undergoing desensitization with Graminaceae pollen extract and mite-enriched house dust. Vasculitis developed 22 months after the first injections, became autonomous after the end of treatment and responded well to systemic corticosteroid therapy in daily doses of 1 mg/kg. The patient was followed up for 8 months during which the vasculitis did not recur, despite reduction in steroid dosage. Reports of necrotizing vasculitis occurring during desensitization seem to be very rare. They raise the problem of whether specific immunotherapy plays a role in the pathogenesis of vasculitis. Most of the characteristics that emerged from the cases previously published are concordant with those found in our patient: the interval between the first injections and the initial symptoms varied from 45 days to 8 years; in every case the condition followed its own course after the injections were discontinued; most patients were being desensitized to several allergens; the cutaneous symptoms were pronounced, eosinophilia was moderate and hepatitis B serology was constantly negative. The few prospective studies aimed at determining, by different methods, the levels of circulating immune complexes (CIC) have given conflicting results. Atopic subjects have high CIC levels, but these do not seem to be influenced by desensitization. The nature of the CIC remains unknown, and the various suggestions put forward (cross-reaction between blocking IgG and auto-antibodies, CIC [blocking IgG, anti-idiotype antibodies]) require confirmation, although the hypothesis of pathogenic CIC (allergen, blocking IgG) is unlikely to be correct.(ABSTRACT TRUNCATED AT 250 WORDS)