A 69-year-old woman presented with an 8-month history of diarrhoea, fresh rectal bleeding, intermittent left-sided abdominal pain, pain in her right elbow and left knee, and a rash on her arms and legs. She had a past history of diverticulosis of the sigmoid colon, an anal fissure (previously biopsied), and mild asthma.

On examination, she was afebrile with mild tenderness in the left iliac fossa. Sigmoidoscopy up to 15 cm showed a layer of pus but normal underlying mucosa, no blood, and one external haemorrhoid. Further physical examination revealed bilateral episcleritis of her eyes, and papular/nodular skin lesions on her palms and legs (Figures 1A,B,C,D). Both her right elbow and left knee were stiff, with mild tenderness on passive movement, and a global reduction in the range of movement.

A distal sigmoid biopsy showed mildly irregular crypts with an occasional crypt abscess. The lamina propria showed a moderate mixed inflammatory cell infiltrate with an occasional cluster of histiocytes forming loose granulomata. Appearances were of active chronic inflammation with a granulomatous component.

A punch biopsy of one of the papular lesions on her right thigh revealed a mild perivascular chronic inflammatory cell infiltrate within the superficial and deep dermis. Loosely formed granulomata (composed of histiocytes and Langhan’s type giant cells with occasional lymphocytes) were scattered within the reticular dermis. Occasionally there was a small amount of degenerate collagen in the centre of a granuloma. There was no palisading typical of the necrobiotic granulomatous conditions. Eosinophils were not a feature.

There was no evidence of vasculitis, panniculitis, atypia, or malignancy. Special stains for fungi and acid fast bacilli were negative. The features were characteristic of granulomatous dermatitis.

The clinical picture in conjunction with the skin, rectal, and sigmoid biopsies and an earlier biopsy of an anal fissure (which had shown granulomata) lead us to believe that the skin lesions were highly likely to be the entity known as metastatic or cutaneous Crohn’s disease.

Up to 50% of patients with Crohn’s disease have at least one extraintestinal manifestation of their inflammatory bowel disease. Cutaneous disorders are commonly associated with Crohn’s disease and may occur in up to 15% of patients. Rarely, patients may develop granulomatous dermatitis at locations remote from the gastrointestinal tract and these lesions are known as metastatic or cutaneous Crohn’s disease.

Cutaneous Crohn’s disease may manifest clinically as nodules, plaques, or ulcers located on the extremities or in intertriginous areas. It is often associated with Crohn’s disease confined to the colon. The presence of lesions does not necessarily relate to the severity of the gastrointestinal disease.

Histologically, as in our case, cutaneous Crohn’s disease is characterised by non-caseating granulomata composed of collections of epithelioid and histiocytic giant cells surrounded by a scant rim of lymphocytes and plasma cells. The aetiology is unknown but the mucosa from the underlying bowel disease is thought to provide the associated immune response responsible for the cutaneous lesions.

As the relationship between the cutaneous lesions and intestinal symptoms is variable, the treatment of gastrointestinal disease may not influence the skin lesions. However, it is generally accepted that the treatment for the cutaneous lesions is treatment of the underlying intestinal disease. Most of these skin lesions will resolve with time with or without treatment.

Author information: Amin Sheikh, House Officer, Department of Surgery; Ali Aldameh, Registrar, Department of Surgery; Pennie Symmans, Pathologist, Department of Pathology; Andrew G Hill, Associate Professor, Department of Surgery; South Auckland Clinical School, University of Auckland, Middlemore Hospital, Otahuhu, Auckland

Correspondence: Associate Professor Andrew Hill, Department of Surgery, South Auckland Clinical School, University of Auckland, Middlemore Hospital, PO Box 93311, Otahuhu, Auckland. Fax: (09) 267 9482; email: ahill@middlemore.co.nz