Dermatitis herpetiformis

A 35-year-old woman attends the surgery complaining of a 4-month history of fatigue. She is experiencing looseness of bowel and abdominal pain. On systematic inquiry, she gives a history of developing a rash that is intensely itchy, which comes and goes but never quite disappears. Examination reveals a widespread symmetrical rash composed of 1 cm papules and small scratched blisters affecting her scalp, elbows, knees and buttocks.

Blood testing reveals a mild anaemia with folate and iron deficiency. Auto antibody testing is positive for immunoglobulin A (IgA) anti-tissue transglutaminase.

What is the SINGLE MOST likely skin condition?

1. Erythema nodosum

2. Pyoderma gangrenosum

3. Dermatitis herpetiformis

4. Acanthosis nigracans

5. Thrombophlebitis migrans

Dermatitis herpetiformis (DH) is an autoimmune blistering skin disease associated with coeliac disease (gluten enteropathy). 15–25% of patients with coeliac disease may develop DH. Thus DH is often considered as a cutaneous manifestation of coeliac disease.

• Acanthosis nigricans is a disorder that may begin at any age. It causes velvety, light-brown-to-black, markings usually on the neck, under the arms or in the groin. It is most often associated with obesity. Acanthosis nigricans can rarely be associated with visceral malignancies such as carcinoma of the stomach.

• Pyoderma gangrenosum are recurring large nodular/pustular ulcers up to 10 cm wide with tender red/blue necrotic edges and can be associated with Crohn's disease, ulcerative colitis and autoimmune hepatitis.

• Thrombophlebitis migrans produces a successive crop of tender nodules affecting blood vessels throughout the body and causes red, tender patches on the skin. It is associated with carcinoma of the pancreas (especially body and tail tumours).

Eczema craquelé

A 67-year-old woman has developed for the first time persistently dry skin on her legs. The skin is rough, sore and looks cracked. With which of the following conditions may this be associated?

1. Hypothyroidism

2. Addison’s disease

3. Type 2 Diabetes Mellitus

4. Coeliac disease

5. Cushing’s disease

This is a case of eczema craquelé, which gets its name from its cracked appearance, it is a frequent type of dermatitis that is a result of dry skin. It is most often seen on the shins, but may also develop on the trunk and upper limbs. Eczema craquelé can develop in anyone with very dry skin. It most often affects the elderly and is also a complication of inherited and acquired forms of ichthyosis. Drugs can also cause eczema craquelé.

Systemic causes of eczema craquelé include:

• Underactive thyroid

• Malnutrition

• Severe weight loss

• Lymphoma

References

• Curriculum Topic Guides: dermatology (RCGP, 2019)

• Eczema: asteatotic eczema (syn. xerotic eczema, eczema craquele) (PCDS)