Necrobiosis lipoidica — SAQ

Stem

A 42-year-old woman with type 2 diabetes presents with slowly enlarging plaques on both anterior shins. They have yellow-brown shiny atrophic centres, prominent telangiectasia and violaceous raised rims. One plaque has developed a shallow painful erosion after minor trauma.^[1]

Questions

a) What is the diagnosis, and which three clinical features support it? (2 marks)^[1]

b) Give two important differential diagnoses and one feature that distinguishes each from this condition. (2 marks)^[2]

c) What investigations or assessments are appropriate, including when biopsy is indicated? (3 marks)^[1][3]

d) Outline stepwise management, including one topical or intralesional treatment and ulcer care. (3 marks)^[3]

Model answer

a) Diagnosis: necrobiosis lipoidica. Supporting features are pretibial anterior-shin plaques, yellow-brown shiny atrophic centre, telangiectasia, violaceous active rim, slow chronic enlargement and diabetes association.^[1]

b) Differentials. Pretibial myxoedema is Graves-related, firm, waxy, non-pitting and mucinous rather than atrophic and telangiectatic. Granuloma annulare is usually a non-atrophic annular ring of papules on the hands or feet and biopsy shows focal palisading granulomas with abundant mucin. Stasis dermatitis causes oedematous eczematous gaiter-zone dermatitis with scale, varicosities and haemosiderin rather than a sharply atrophic yellow plaque.^[2]

c) Investigations and assessment. If classic, NL is primarily clinical. Check HbA1c or fasting glucose, assess diabetic complications, pulses, neuropathy, venous oedema, smoking and thyroid symptoms or TSH if clinically indicated. Biopsy the active raised border if the lesion is atypical, extratibial, nodular, rapidly changing, ulcerated suspiciously or diagnosis is uncertain; histology shows palisading or layered granulomas around necrobiotic collagen with plasma cells and vascular thickening. In an ulcer, assess infection and perfusion and biopsy a raised, rolled, bleeding or non-healing edge to exclude SCC.^[1][2][3]

d) Management. Explain chronicity and that glycaemic control is important for health but does not reliably clear NL. Advise smoking cessation, trauma avoidance, emollients, shin protection and non-adherent dressings. Treat active inflammation at the rim with clobetasol propionate 0.05 percent ointment once daily for 2 to 4 weeks or intralesional triamcinolone 5 to 10 mg/mL into the active rim every 4 to 6 weeks; avoid the atrophic centre. Tacrolimus 0.1 percent ointment twice daily, phototherapy, pentoxifylline, antiplatelet therapy or biologics are specialist options for refractory disease. Ulcers need wound care, vascular assessment, compression if venous disease and arterial supply permit, infection treatment only when clinically infected, and biopsy of suspicious chronic edges.^[3]

References3ShowHide

1. [1]Lima AL, Illing T, Schliemann S, et al. Cutaneous Manifestations of Diabetes Mellitus: A Review. American Journal of Clinical Dermatology, 2017.PMID 28374407
2. [2]Terziroli Beretta-Piccoli B, Mainetti C, Peeters MA, et al. Cutaneous Granulomatosis: a Comprehensive Review. Clinical Reviews in Allergy & Immunology, 2018.PMID 29352388
3. [3]Erfurt-Berge C, Renner R, Peckruhn M, et al. S1-Guideline for diagnosis and therapy of necrobiosis lipoidica. Journal der Deutschen Dermatologischen Gesellschaft, 2026.PMID 41420334