Localised chronic fibrosing vasculitis versus erythema elevatum diutinum

A woman in her 70s was referred for a painless plaque on the shin, present for 2 years and progressing in thickness. Examination revealed a large erythematous to violaceous indurated plaque with cobblestone appearance. Biopsy revealed an inflammatory infiltrate of neutrophils with scattered histiocytes, lymphocytes, eosinophils and plasma cells interspersed with areas of lamellar fibrosis and focal areas of vascular damage, suggestive of a localised chronic fibrosing vasculitis of the skin. Localised chronic fibrosing vasculitis is a rare dermatosis, typically presenting as ulcerated violet-red nodules, which can appear histologically similar to erythema elevatum diutinum (EED), which typically presents as red-brown annular plaques. EED may have a predominance of neutrophils and granulomas, while chronic fibrosing vasculitis may have a sparse infiltrate of mixed inflammatory cells without granulomas. While dapsone is a first-line treatment for EED, there are no formal guidelines on the treatment of localised chronic fibrosing vasculitis. Given the neutrophils in this sample and similarities with EED, this patient was treated with oral dapsone, resulting in plaque improvement.