Erythema induratum (nodular vasculitis) associated with Crohn's disease: a rare type of metastatic Crohn's disease.

We herein report a patient with erythema induratum/nodular vasculitis (EI/NV) associated with Crohn's disease (CD), which is considered to be a rare type of metastatic CD. A 54-year-old woman, who had a history of CD, presented with erythematous nodules on her legs. The histopathological features of the skin biopsy revealed a granulomatous, mixed septal and lobular panniculitis, which was characterized by many discrete epithelioid cell granulomas (necrobiotic/necrotizing-type and sarcoidal type), necrosis of the adipocytes, and granulomatous phlebitis in the muscular wall of a subcutaneous vein. A review of the pertinent literature and the presented case suggested the following: (1) panniculitis associated with CD may be either an erythema nodosum type or an EI/NV type; (2) so far, the reported cases of metastatic CD or granulomatous vasculitis in CD rarely presented with granulomatous panniculitis without dermal involvement, and most cases showed histopathological features that were similar to or indistinguishable from those of EI/NV; and (3) the finding of granulomatous vasculitis (especially the presence of discrete epithelioid cell granulomas involving the veins or venules) may be a characteristic feature of EI/NV associated with CD, in contrast to the finding of acute vasculitis, which is typically present in patients with EI/NV due to causative factors other than CD.