Arthus-type insulin reaction

Another manifestation of insulin allergy, which is also now rare, is a delayed local reaction to injected insulin. This presents as a tender subcutaneous lump developing at the injection site half an hour or so after injection and lasting for 12-24 h. This is a local Arthus-type reaction, mediated by IgG rather than IgE, and is due to complement activation by insulin-IgG immune complexes. It often responds to addition of hydrocortisone to the injected insulin. 

A 68-year-old man with type 2 diabetes treated with insulin and oral hypoglycemic agents developed pruritic plaques of more than 15 cm diameter at the site of his insulin injections. Skin biopsy showed an Arthus type reaction. Various insulin therapies, including insulin glargine, insulin detemir, and human insulin, produced the same response. Intra-dermal tests were positive to a variety of insulins and protamine. He was desensitized using subcutaneous human insulin and orally fexofenadine 180 mg bd and was then successfully treated with insulin glargine. The fexofenadine was stopped 6 months later. 

A 45-year-old woman who had used insulin for 4 years had a biphasic hypersensitivity reaction to human insulin (or another component of the injection fluid) (135). Within 20 minutes after the injection a swelling developed and in a later phase papular lesions with lichenoid features and post-inflammatory hyperpigmentation emerged. Histologically, there was neutrophilic infiltration with erythrocyte extravasation and eosinophilic amorphous material, surrounded by neutrophilic infiltrate. Saline injection did not elicit an effect. IgE anti-insulin antibodies were not found. There was no Arthus reaction (type IV allergy). 

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See also in sourсe #XX -- [ ]

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