This pruritic, eruption with yellowing atrophy and telangiectasias on the lower extremities is a classic presentation for necrobiosis lipoidica (NL).
NL is a chronic granulomatous disorder with a predilection for the lower extremities. Patients with NL present with progressive, yellow-brown atrophic plaques on the pretibial aspect of the legs. The plaques have underlying telangiectasias, revealed by the atrophy, and may ulcerate. While these lesions are primarily asymptomatic, associated symptoms may include pruritus, pain, or altered sensation on the affected skin. The classic pathology of NL is notable for altered collagen bundles layered with palisading granulomas extending deep into the dermis. Other notable findings may include mixed inflammatory cells, multinucleated giant cells, and plasma cells; mucin is notably absent.
There is an established relationship between NL and diabetes. When these 2 entities are present, the skin eruption may be referred to as “necrobiosis lipoidica diabeticorum” or “NLD.” Only a small percentage of patients with diabetes will develop NL. Furthermore, there is growing evidence to suggest that NL may be associated with other comorbidities, such as obesity, hypertension, dyslipidemia, and thyroid disease.1 Additionally, squamous cell carcinoma has been reported as arising within skin affected by NL.2
The etiology of NL is not completely understood. Current theories suggest that blood vessel inflammation related to autoimmune factors may be at work.2 The differential diagnosis of NL includes granuloma annulare, pretibial myxedema, stasis dermatitis, panniculitis, morphea, and lichen sclerosis.
NL can be refractory to therapy. Paramount to management is the avoidance of trauma to the affected skin. Topical therapies include corticosteroids, tretinoin, and tacrolimus. Systemic immunomodulation with infliximab, etanercept, thalidomide, and cyclosporine has also been trialed. There is evidence for the utility of pentoxifylline (400 mg po tid), a xanthine derivative often used for peripheral artery disease, to reverse ulceration that can arise in NL.
The patient in this case opted for topical therapy with clobetasol 0.05% ointment and tacrolimus 0.1% ointment. She was subsequently lost to follow-up.
Image courtesy of Cyrelle Fermin, MD, Department of Dermatology, University of New Mexico School of Medicine, Albuquerque. Text courtesy of Cyrelle Fermin, MD, and Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque.