Necrobiosis lipoidica

Necrobiosis lipoidica is an uncommon skin condition characterised by sharply demarcated, atrophic yellowish patches or plaques on the shins. It was first described in patients with insulin-dependent diabetes but it can affect non-diabetics as well. 

This chapter is set out as follows:

• Vascular changes may play a role 
• Necrobiosis lipoidica is associated with diabetes, the reasons remain unclear 

• Necrobiosis lipoidica has a gradual onset
• Although necrobiosis lipoidica can affect any age, it most commonly presents in young adults and early middle age. Patients with insulin-dependent diabetes tend to present at an earlier age when compared to non-insulin-dependent patients 
• Females are affected more than males in a 3:1 ratio 
• In many cases lesions are asymptomatic, although some patients experience pain 
• The main complaint is the unsightly appearance of the lesions

Distribution

• Lesions typically affect both shins, although necrobiosis lipoidica is sometimes unilateral and other sites can be affected

Morphology

• Typically, one or more yellowish patches / plaques
• Lesions grow with an erythematous edge, and a centre that becomes shiny and atrophic with prominent telangiectasia
• Ulceration can occur
• Slow expansion over many years is usual, although lesions may go through periods of being more, and less, active 

• It is important to investigate for diabetes mellitus

• The diagnosis is usually clinical, although sometimes a biopsy is needed if the presentation is atypical as cutaneous sarcoid can occasionally mimic necrobiosis lipoidica

• Histology shows changes involving the full thickness of the dermis, often extending into the subcutaneous fat. Early lesions show a perivascular and interstitial mixed inflammatory cell infiltrate. A granulomatous inflammatory reaction is seen around areas of destroyed collagen. Areas of necrobiosis are usually more extensive and less well-defined than in granuloma annulare

Step 1: general measures

• Provide a patient information leaflet
• Smoking cessation may help
• Due to the increased risk of ulceration, advise the patient to avoid traumatising the skin
• Not all cases require treatment

Step 2: topical steroids 

• A decision to treat necrobiosis lipoidica needs careful discussion with the patient - at best, individuals can expect a mild-moderate improvement, and one has to weigh up the possible risks of steroid atrophy
• If treatment is given use a potent topical steroid, eg 0.1 % betamethasone cream (or ointment) once a day, and advise application only to the leading inflammatory edge and not the atrophic centre. The effectiveness of treatment can sometimes be enhanced by using occlusion eg Clingfilm
• Photograph the lesion / lesions and review three months after starting the treatment to assess response

Step 3: steroid sparing therapy 

• If there are concerns with regards to steroid atrophy, consider a trial of 0.1% tacrolimus ointment BD 

Step 4: ulcerated lesions

• Consider treating more aggressively, for example:
  • 0.1% betamethasone (or Dermovate ®) cream / ointment under occlusion with Clingfilm, Zipzocs ®, or Viscopaste ® bandages
  • Again, photographs are useful to monitor progress

Step 5: Secondary Care

• Patients with troublesome, recalcitrant lesions, especially if ulcerated, should be referred to Dermatology
• Phototherapy (especially PUVA) leads to improvements in some cases 
• Other options include the careful administration of intralesional steroids in to the expanding edge, and short-term ciclosporin
• Occasionally a chronic, ulcerated lesion can transform in to a squamous cell carcinoma. Refer suspect lesions urgently (two-week wait)