Necrobiosis lipoidica

What is necrobiosis lipoidica?

Necrobiosis lipoidica is a rare granulomatous skin disorder which can affect the shin of insulin-dependent diabetics, although it may occur in non-diabetic subjects as well. The cause is unknown.

Who gets necrobiosis lipoidica?

Necrobiosis lipoidica is three to five times more common in females than in males.  

• 0.3% of patients with diabetes have necrobiosis lipoidica.
• It can occur in both type 1 and type 2 diabetes.
• 11–65% of patients with necrobiosis lipoidica have diabetes or prediabetes.
• Diabetes associated with necrobiosis lipoidica can be well controlled or poorly controlled.
• Patients with diabetes are more likely to be younger or male than those without diabetes.
• Other associations include obesity, hypertension, dyslipidaemia and thyroid disease.

What are the clinical features of necrobiosis lipoidica?

Typically in necrobiosis lipoidica, one or more yellowish brown patches develop slowly on the lower legs over several months.

• Necrobiosis lipoidica most often occur on both shins and are rarely found in other sites.
• The plaques may be asymptomatic or tender.
• The plaques may persist for years.
• They may be round, oval or an irregular shape.
• The centre of the patch becomes shiny, pale, thinned, with prominent blood vessels (telangiectasia).
• A minor injury to an established patch can cause it to ulcerate. The ulcers may be very painful or painless.
• Ulcers due to necrobiosis lipoidica are at risk of secondary bacterial infection and delayed healing.

How is the diagnosis of necrobiosis lipoidica made?

The diagnosis of necrobiosis lipoidica may be made clinically. A skin biopsy may be performed to confirm the diagnosis. The histopathology is characteristic; it shows a granulomatous inflammatory reaction around destroyed collagen. This is known as necrobiosis or collagenolyis. It can be difficult to distinguish from granuloma annulare and rheumatoid nodule.

What is the treatment for necrobiosis lipoidica?

Not all cases of necrobiosis lipoidica require treatment. The following treatments are sometimes effective:

• Topical steroids, usually under a plastic occlusive dressing
• Intralesional steroid injections or steroid tablets
• Aspirin and dipyridamole combination
• Oxypentifylline tablets
• Niacinamide
• Oral ciclosporin
• Biologic agents
• Photochemotherapy (PUVA)
• Photodynamic therapy
• Fumaric acid esters.

Ulcerating necrobiosis lipoidica may require aggressive treatment.