Metastatic Crohn's disease (MCD) indicates the presence of non-caseating granuloma of the skin at sites separated from the gastrointestinal tract by normal tissue and is the least common dermatologic manifestation of CD. In adults, MCD usually appears after the initial diagnosis of CD in 70% of cases, whereas in children, it appears at the same time as CD in almost half of the cases. The most frequent skin lesions in adults are nodules, plaques with or without ulceration on the extremities and ulcers on the genitals. In children, genital swelling with or without erythema is the most frequent presentation of MCD. Simultaneous presence of perianal CD affects more females (60%) and particularly children. Associated gastrointestinal symptoms are present in one third of the cases in adults and in half of the cases in children. Treatment is often unsatisfactory. Randomised controlled trials are lacking. Various chemotherapeutic agents have been used such as oral metronidazole, topical and/or oral steroids, azathioprine, cyclosporine, sulfasalazine, tetracyclines, topical or systemic tacrolimus, infliximab alone or with methotrexate, and surgical treatment with oral zinc sulphate. MCD represents another 'great imitator'. This reviews the most relevant characteristics of this disease, in order to increase awareness and to avoid delay in diagnosis and improve management of the whole CD complex.

Spontaneous complete regression of multiple Bowen's disease in the web-spaces of the feet. Int J Dermatol 2006; 45: 783-785. 4 Wong TW, Sheu HM, Lee JY, Fletcher RJ. Photodynamic therapy for Bowen's disease (squamous cell carcinoma in situ) of the digit.