Patch testing in prurigo nodularis.

32 patients with prurigo nodularis evaluated at the Mayo Clinic from 1975 to 1987 have been patch tested for sensitivity to appropriate allergen series; 25 of these had relevant positive reactions and subsequent follow-up to 5 to 14 years was available for 11. 6 patients had persistent disease and 5 had resolution or marked improvement. 3 of these latter patients noted a strong positive correlation between improvement and avoidance of contact allergens. Screening for contact sensitivity may be helpful in the management of this refractory dermatosis, particularly if there is a coexistent dermatitis.