Symmetrical intense itching
Last reviewed: April 2025
Author(s): Dr Ian Coulson, Dermatologist, United Kingdom (2025).
Edited by the DermNet content team.
Background
This 60 year-old lady has developed intense itching symmetrically over her knees, elbows, sacrum and scalp. She had noticed tiny blisters in the affected areas, but because she is so itchy she has scratched and ruptured them.
Describe what you see.
2 to 3 mm clustered erosions can be seen overlying the patella. The lesions are arranged in clusters, simulating the lesions seen in herpes simplex.
With her symptoms, and the appearances of the rash, what is the likely diagnosis?
The intense itching, and symmetrical distribution over the elbows and knees, sacrum and scalp suggest that this is dermatitis herpetiformis, and acquired vesicobullous eruption associated with gluten sensitive enteropathy.
What tests can confirm your diagnostic suspicion?
If a vesicle or blister is identified, then a biopsy will show a subepidermal vesicle, and a collection of neutrophils are often seen in the papillary dermis at the edge of the vesicle.
The diagnostic test is direct immunofluorescence of perilesional skin which shows granular deposits of IgA.
Coeliac serology is often positive.
How can this condition be treated?
Administration of dapsone will stop the itching often within 48 hours, and the lesions will heal within a week or so.
Because the condition is invariably associated with gluten sensitive enteropathy, on diagnosis confirmation, a gluten-free diet for life should be started.
