Necrobiosis Lipoidica

Necrobiosis lipoidica (NL) is a rare, chronic granulomatous disorder of collagen degeneration, producing yellow brown atrophic plaques, most often on the shins, and strongly associated with diabetes.

• Prevalence is 0.3 to 1.2% of patients with diabetes; about 60% of NL patients have diabetes, and many others have impaired glucose tolerance or family history of diabetes.
• Female to male ratio 3:1; onset 30 to 50 years (earlier in type 1 diabetes).
• Pathogenesis: microangiopathy, abnormal collagen, and granulomatous inflammation.
• Ulceration in 25 to 35%; squamous cell carcinoma has been reported rarely in chronic lesions.

• Well circumscribed, indurated plaques with a yellow brown atrophic, shiny centre, prominent telangiectasia, and a violaceous raised border; commonly bilateral on the pretibial areas.
• Rare on face, scalp, arms, and feet.
• Mostly asymptomatic; may be tender, especially with ulceration (painful ulcers).
• Koebner phenomenon after trauma; slow progression and chronic course, with spontaneous resolution in 10 to 20%.

• Clinical diagnosis; biopsy (including subcutis) if atypical: palisading granulomas around degenerated collagen ("layered" pattern), horizontally arranged granulomas, plasma cells, and thickened vessel walls.
• Screen for diabetes (HbA1c, fasting glucose, OGTT), lipids, and thyroid function.
• Exclude granuloma annulare, sarcoidosis, morphoea, venous stasis dermatitis, and cutaneous infections (leprosy, atypical mycobacteria).
• Doppler studies if ulcerated, and biopsy any non-healing ulcer to exclude SCC.

• Optimise glycaemic control (although it does not consistently influence NL), manage lipids, and stop smoking.
• Protect shins from trauma; compression stockings.
• Topical and intralesional: clobetasol 0.05% ointment daily to the active border for 4 to 6 weeks (atrophy risk), intralesional triamcinolone 2.5 to 5 mg/mL into the active edge every 4 weeks, tacrolimus 0.1% ointment.
• Systemic options (case series evidence): pentoxifylline 400 mg three times daily, aspirin 75 to 100 mg, hydroxychloroquine 200 mg twice daily, fumaric acid esters, mycophenolate 1 g twice daily, ciclosporin 3 to 5 mg/kg, TNF inhibitors (infliximab 5 mg/kg, adalimumab, etanercept), and JAK inhibitors.
• Phototherapy (PUVA, UVA1) and photodynamic therapy; pulsed dye laser for telangiectasia.
• Ulcers: moist wound care, compression, and surgical excision with grafting only when quiescent.