Pictorial Case Study: Blistering rash

The Case - This 32-year-old woman attended the surgery complaining of a recurrent, very itchy, papular, blistering rash. It had appeared over her knees, elbows, buttocks and scalp.

Dermatitis herpetiformis: autoimmune disease (Photograph: Author image)
Dermatitis herpetiformis: autoimmune disease (Photograph: Author image)

She had applied calamine lotion and tried an oral antihistamine, without benefit. On examination there were obvious papules, vesicles and blisters and excoriated lesions over the buttocks and upper thighs and signs of scars from scratch marks in other areas. There were no digestive symptoms, such as indigestion, bloating, change in bowel habit or weight loss.

Diagnosis and Management
A possible diagnosis of dermatitis herpetiformis (DH) was made. DH is a genetically linked, autoimmune disease associated with a gluten sensitive enteropathy. The rash develops as the result of the deposition of IgA in the papillary dermis, caused by an immunological response to chronic stimulation of the mucosa of the gut by gluten.

However, many patients with this condition have no GI symptoms. About 15-25 per cent of patients with coeliac disease develop DH. DH is more common in northern Europe, it usually presents in the 20 to 40 year age group and is more common in men.

The diagnosis is confirmed by direct immunofluorescence of a skin biopsy. Serum markers, such as IgA endomysial antibodies, may be positive.

The main approach to treatment is to advise the patient on a gluten-free diet. The diet must be adopted for life but it may take several months for improvement to occur. Dapsone is usually added initially and should achieve dramatic improvement. Itching in this patient settled within 24 hours.

Patients on long-term treatment with dapsone are at risk of developing blood disorders and acute haemolytic anaemia or agranulocytosis that would make them susceptible to infections. This is a particular risk for patients with glucose-6-phosphate dehydrogenase deficiency. This level should be checked before starting the medication and the patient warned to report any such problems promptly.


  • Bullous pemphigoid.
  • Erythema multiforme.
  • Dermatitis artefacta.
  • Scabies.
  • Eczema.
  • Papular urticaria.


Bullous pemphigoid

  • Thought to be caused by IgG immunoglobulins and activated T-lymphocytes that attack proteins causing an autoimmune reaction to the proteins.
  • Tends to occur in middle age and the elderly.
  • Itchy and tense blisters especially in the flexures. May affect the mouth.
  • Diagnosis confirmed by biopsy of a typical blister and by direct immunofluorescence.
  • Systemic steroids (prednisolone) starting with 40-80mg daily.
  • Very potent topical steroids may be sufficient for mild or localised cases and may be tried first or as an adjunct to systemic therapy. Tetracycline or nicotinamide may also be tried.
  • Other drugs that may be used in resistant cases are azathioprine, methotrexate, cyclophosphamide and ciclosporin.
  • Severe cases may require hospital admission.
  • Remission usually occurs within five years.

Contributed by Dr Jean Watkins, a retired GP in Hampshire.

Have you registered with us yet?

Register now to enjoy more articles and free email bulletins


Already registered?

Sign in

Follow Us:

Just published

Vaccination tracker

UK COVID-19 vaccination programme tracker

GPs across the UK have led the largest-ever NHS vaccination programme in response...

RCGP chair Professor Martin Marshall

Hand PCNs control of primary care infrastructure funding, says RCGP

CCG funding for primary care infrastructure should be handed to PCNs when the bodies...

Professor Martin Marshall and Talking General Practice logo

Podcast: RCGP chair Professor Martin Marshall

Talking General Practice speaks to RCGP chair Professor Martin Marshall.

Dr Chaand Nagpaul

In-house review not enough to stop 'unjust' GMC referrals, warns BMA

Doctors' leaders have repeated calls for a full independent review of the GMC referral...


How widespread is long COVID in the UK?

Millions of people in the UK are living with long COVID. GPonline looks at the data...

COVID-19 vaccination sign

GP contract for autumn COVID-19 booster campaign due shortly

GP practices in England will be invited shortly to sign up for the COVID-19 autumn...