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.
What are the clinical features of necrobiosis lipoidica?
Typically in necrobiosis lipoidica, one or more tender yellowish brown patches develop slowly on the lower legs over several months. They 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. This is often painless, but is 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. Skin biopsy may be performed to confirm the diagnosis. The histopathology is characteristic; it shows an granulomatous inflammatory reaction around destroyed collagen. This is known as necrobiosis or collagenolyis. It can however be difficult to distinguish from granuloma annulare and rheumatoid nodules.
What is the treatment for necrobiosis lipoidica?
Not all cases require treatment. The following are sometimes effective:
- Topical steroids, usually under a plastic occlusive dressing
- Intralesional steroid injections or steroid tablets
- Aspirin and dipyridamole combination
- Oxypentifylline tablets
- Oral ciclosporin
- Biologic agents
- Photochemotherapy (PUVA)
Ulcerating necrobiosis lipoidica may require aggressive treatment.