Derm Dx: Ulcerated lesion on the shins of a patient with type 1 diabetes

Necrobiosis lipoidica diabeticorum (NLD) is a rare chronic granulomatous disease that affects patients with diabetes mellitus. The name necrobiosis lipoidica is often used in cases that do not involve diabetes. The most frequent location for NLD is the pretibial area....

Submit your diagnosis to see full explanation.

Necrobiosis lipoidica diabeticorum (NLD) is a rare chronic granulomatous disease that affects patients with diabetes mellitus. The name necrobiosis lipoidica is often used in cases that do not involve diabetes.

The most frequent location for NLD is the pretibial area. Other sites of involvement include ankles, calves, thighs, and feet. NLD is less commonly found above the waist.

NLD skin lesions typically begin as 1 to 3 mm, well-circumscribed papules that slowly coalesce into plaques. The plaques initially appear red-brown and later progress to yellow-brown atrophic plaques with telangiectasia. Most patients present with multiple bilateral NLD lesions.

About one-third of lesions become ulcerated, usually after trauma. Although the majority of lesions are painless because of associated nerve damage, up to 25% of NLD lesions can be extremely painful — especially if ulcerated.

In terms of epidemiology, there is a female predominance (female to male ratio of 3:1). The disease is rare; the incidence rate of NLD among patients with diabetes is 0.3 to 1.2%. In patients with type 1 diabetes, the age of onset is typically around the third decade of life. In patients with type 2 diabetes, or no diabetes, the age of onset is usually the fourth decade of life.

The exact cause for NLD is unclear. Diabetic microangiopathy is thought to be associated because small vessel damage is often observed. NLD presents histopathologically with interstitial and palisaded granulomas that diffusely involve the dermis and sometimes the subcutaneous fat. At low magnification, the granulomas can be observed in a distinct, tier-like (layered) pattern.

Fully developed lesions typically contain predominantly lymphocytes and histiocytes, with occasional multinucleated cells. Plasma cells are characteristic.

Diagnosis is typically based on clinical factors. However, if uncertain, a skin biopsy may be performed. The early forms of NLD may be especially hard to recognize.

The differential diagnosis includes granuloma annulare, sarcoidosis, and xanthomas.

Necrobiosis lipoidica diabeticorum is typically chronic and difficult to treat. Current reliable therapeutic options are minimal. Even in patients with well-controlled diabetes, NLD may not resolve. Spontaneous remission is possible but is unpredictable.

Therapy for NLD is primarily symptomatic. Topical and intralesional corticosteroids are applied to active borders of lesions to reduce inflammation and halt progress. Ulcerated lesions are treated with local wound care.

Emily Guo is a medical student at Baylor College of Medicine.

Adam Rees, MD, a graduate of the David Geffen School of Medicine at UCLA, practices dermatology in Los Angeles.