THE FIRST PATHOLOGICAL SPECIMEN FROM A RARE LOCAL REACTION AFTER SUBCUTANEOUS ALLERGEN IMMUNOTHERAPY

Abstract

Introduction Local reactions in the form of injection site tenderness, pain, induration, and erythema are frequently experienced in subcutaneous allergen immunotherapy (SCIT). We describe a case of bullous vesicles forming in a delayed local reaction to SCIT. We also provide the results of biopsies to consider possible mechanisms of action. Case Description A 57-year old male with a history of allergic rhinitis presented 24 hours after SCIT administration, due to the formation of blistering lesions at the injection site. He denied pruritus, burning, or systemic symptoms. He had been receiving SCIT for 7 months and was on maintenance dosing. On exam, multiple tense bulla containing clear, yellow fluid were observed at the injection site. Histological exam showed a non-specific sub-epidermal vesicular dermatitis. Direct immunofluorescence staining using IgA, IgG, IgM, C3, and fibrinogen revealed no pattern of antibody deposition. Vesicular fluid stains and cultures had no growth of bacterial or fungal organisms. The patient wished to continue SCIT, which was resumed at a decreased dose. He subsequently built back up to maintenance dosing with no further reactions. Discussion Frequently, local reactions to SCIT are associated with erythema, tenderness, and induration. To our knowledge, there has been only one case report of a local reaction resulting in bulla formation from SCIT, however no skin biopsy was obtained. Our biopsy suggests the patient's symptoms do not appear typical of any understood autoimmune, antibody-dependent bullous processes. Local reactions in the form of injection site tenderness, pain, induration, and erythema are frequently experienced in subcutaneous allergen immunotherapy (SCIT). We describe a case of bullous vesicles forming in a delayed local reaction to SCIT. We also provide the results of biopsies to consider possible mechanisms of action. A 57-year old male with a history of allergic rhinitis presented 24 hours after SCIT administration, due to the formation of blistering lesions at the injection site. He denied pruritus, burning, or systemic symptoms. He had been receiving SCIT for 7 months and was on maintenance dosing. On exam, multiple tense bulla containing clear, yellow fluid were observed at the injection site. Histological exam showed a non-specific sub-epidermal vesicular dermatitis. Direct immunofluorescence staining using IgA, IgG, IgM, C3, and fibrinogen revealed no pattern of antibody deposition. Vesicular fluid stains and cultures had no growth of bacterial or fungal organisms. The patient wished to continue SCIT, which was resumed at a decreased dose. He subsequently built back up to maintenance dosing with no further reactions. Frequently, local reactions to SCIT are associated with erythema, tenderness, and induration. To our knowledge, there has been only one case report of a local reaction resulting in bulla formation from SCIT, however no skin biopsy was obtained. Our biopsy suggests the patient's symptoms do not appear typical of any understood autoimmune, antibody-dependent bullous processes.