Necrobiotic lesions of the skin: an approach and review of the literature

Necrobiosis refers to the degeneration of collagen fibres which is central to necrobiotic dermatitides. We describe these necrobiotic dermatitides; namely granuloma annulare, rheumatoid nodule, necrobiosis lipoidica and necrobiosis xanthogranuloma with an approach to diagnosis, clinical presentation and treatment options. In most instances, the diagnosis can be easily reached; however, at times this can be difficult and may require additional steps, including detailed clinical history, special stains, immunohistochemical stains and a repeat biopsy if necessary.