An 18-year-old boy with type 1 diabetes mellitus, presented to our dermatology clinic with a 3-year history of enlarging asymptomatic plaques on his legs, dorsum of hands and his abdomen. On physical examination two atrophic, yellowish plaques on left leg, one larger plaque on left ankle, an erythematous atrophic plaque on left hand and a smaller annular lesion on the abdomen were observed that had telangiectasias in the center and also peripheral elevated erythematous papules. The patient’s diabetes was well-controlled and he did not show any sign of retinopathy, neuropathy or nephropathy. The patient was treated with topical tacrolimus 0.1% and intralesional steroid in the margin.
Multiple arborising telangiectatic vessels, intermixed with thin hairpin-like vessels were seen on a mixed pink, white and yellowish background on dermoscopy (Figure 1).
A skin biopsy revealed layers of granulomatous lymphohistiocytic infiltrations and alternating necrobiosis and fibrosis, which were compatible with Necrobiosis Lipoidica (NL).
NL is a non-infectious granulomatous disease of the skin that usually presents as shiny atrophic telangiectatic yellow-brown plaques on the shins 1 (Figure 2). Women are more commonly affected than men. NL lesions are often painless but they could be painful if ulcerated 2. NL is histologically characterized by collagen degeneration and thickening of blood vessels. It is seen among 0.3-1.2% of all diabetic patients; while nearly two thirds of patients with NL have diabetes 1. NL is more commonly diagnosed after the diabetes, but it may precede diabetes or happen concurrently. Although the exact pathogenic mechanism is not yet clear, many patients with both diabetes and NL were shown to have poor glycemic control, so a microangiopathic etiology for the development of these skin lesions have been proposed 3. The main dermoscopic findings of NL are the presence of branching telangiectasias, hairpin-like vessels, and a yellowish background 4,5. Dermoscopy may be helpful for differentiating NL from other granulomatous disorders 4,5. Therapeutic modalities such as topical and intralesional steroids, topical tacrolimus, cyclosporine, mycophenolate mofetil, ASA and clofaziminehave had limited success 2, but improvement in glycemic control may particularly lead to NL resolution in type-1 diabetic patients 3.