Management of necrobiosis lipoidica

The significance of necrobiosis lipoidica includes its relationship to insulin dependent diabetes mellitus, its tendency to break down into painful ulcers, an − albeit rare − association with squamous cell carcinoma and, by no means least, its cosmetic impact, occurring as it does on the shins of young and middle‐aged women. It is a degenerative disease of collagen in the dermis and subcutaneous fat but very little is known about its aetiology. The most popular theories are that it has a microangiopathic basis, is the result of vascular occlusion, is due to immune complex formation, or is a consequence of abnormal glucose transport by cutaneous fibroblasts. The histology of necroblosis lipoidica offers few clues about aetiology and is characterized by a diffuse, tiered granulomatous dermatitis extending down to the panniculus, with palisades of histiocytes around zones of degenerated collagen bundles. With the passage of time, progression to sclerosis of the reticular dermis and subcutaneous fat occurs. In early lesions, a neutrophilic vasculitis may be evident. In the absence of knowledge regarding the aetiology, there is at present no rational therapy for necroblosis lipoidica and our relative ignorance has spawned a wide variety of treatments over the years, most of which are of doubtful benefit but some of which appear to have potential. The majority of the literature on the treatment of necrobiosis lipoidica refers to anecdotal reports and there is a paucity of controlled trials. The main modalities of therapy include: nonspecific anti‐inflammatory agents, such as topical, intra‐lesional and systemic corticosteroids; drugs acting on the haemostatic mechanisms, such as an aspirin/dipyridamole combination and pentoxifylline; physical techniques, such as excision/grafting and laser surgery; enhancement of wound healing, such as hyperbaric oxygen, tissue‐engineered human dermis, GM‐CSF and becaplermin; and immunomodulatory drugs, such as cyclosporin and mycophenolate mofetil. There has been a particular recent interest in photochemotherapy, with several different groups reporting the benefits of topical PUVA in both ulcerated and nonulcerated necrobiosis lipoidica. However, there have not as yet been any controlled clinical trials, and PUVA would lend itself to within‐patient comparison. The cosmetic effect of tanning would need to be assessed and consideration given to the potential for increasing the risk of squamous cell carcinoma. The immunomodulatory property of PUVA may be a possible mechanism of its action.