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Blistering eruption and history of Crohn disease
Last reviewed: December 2022
Author: Dr Ian Coulson, Consultant Dermatologist and Editor-in-Chief, 2022.
Edited by the DermNet content department
Background
A 67-year-old man gives a six-week history of a progressive, itchy, and blistering eruption affecting his limbs. There has been no involvement of his mucous membranes. He has a 10-year history of Crohn disease.
What is this likely condition?
What diagnostic physical sign does the image demonstrate?
There are blisters arranged in a ring — the so-called “string of pearls” sign, which is most often seen in this condition.
Perilesional immunofluorescence will show a linear band of IgA at the dermoepidermal junction, in contrast to the granular deposits of IgA seen in dermatitis herpetiformis. The blisters are sub-epidermal. As opposed to dermatitis herpetiformis, linear IgA disease is not associated with gluten enteropathy.
Name three conditions that may be associated with this disease
Linear IgA disease may be associated with solid cancers and lymphomas, inflammatory bowel disease, and rheumatoid disease. Several drugs have been implicated in initiating this condition.
Name the two most frequently successful systemic therapies
Treatment of this condition involves the use of potent topical steroids, but oral steroids combined with oral dapsone are usually required.