Non-infectious Granulomatous Diseases of the Skin and their Associated Systemic Diseases: An Evidence-based Update to Important Clinical Questions

Elena Balestreire Hawryluk; Leonid Izikson; Joseph C. English III

Disclosures

Am J Clin Dermatol. 2010;11(3):171-181. 

In This Article

7. Why Does Metastatic Crohn Disease Persist after Surgical Removal of the Affected Bowel?

Crohn disease is a chronic inflammatory bowel disease characterized by episodic inflammation and gastrointestinal and systemic symptoms. There are three types of cutaneous lesions found in Crohn disease: (i) granulomatous perianal and peristomal lesions that occur in about one-third of patients; (ii) oral lesions; and (iii) rare metastatic cutaneous Crohn disease (MCD), which occurs at sites that are not contiguous with, but are histopathologically identical to, the granulomatous inflammation in the gastrointestinal tract. MCD lesions are typically non-healing ulcers on limbs and in skin folds.

There is no correlation between the appearance of gastrointestinal and skin lesions. In 20% of cases, MCD precedes the diagnosis of intestinal Crohn disease, with skin lesions occurring 3 months to 9 years prior to gastrointestinal disease,[96,97] and it has been proposed that the timing of cutaneous and gastrointestinal disease presentation may be related to age.[98] It was first postulated thatMCDlesions are caused by deposits of immune complexes in the skin,[99] which ultimately result in granulomatous reactions. Alternatively, it has been proposed that a type IV hypersensitivity reaction, mediated by T cells, causes granuloma formation and vascular damage.[100] Additional research has suggested a potential role for other proteins, genes, or cells as recently reviewed by Palamaras et al.[101] A 2003 retrospective dermatopathology study of 33 patients with Crohn disease identified bacterial ribosomal RNA in patients' gastrointestinal tract lamina propria, but was unable to find evidence of microbial ribosomal RNA in corresponding skin biopsies; the authors suggested that the cutaneous lesions may represent an excessive immune response to the bacterial fragments.[102] Numerous environmental antigenic triggers on the skin may continue to promote the cutaneous disease process after the initialMCDgranulomatous lesions appear, independent from the gastrointestinal disease activity. Furthermore, lymphedema is often associated with MCD as well as Crohn disease,[103,104] and may contribute to the persistence of cutaneous lesions through the compromised clearance of such an antigen.

Given these recent data, along with the apparent independence of cutaneous and gastrointestinal lesions with respect to onset and response to treatment, it is not surprising that surgical excision of gastrointestinal lesions does not necessarily cause therapeutic improvement in cutaneous lesions. While cutaneous lesions may improve with treatment of gastrointestinal disease, even the surgical removal of involved bowel lesions does not necessarily have therapeutic effects on cutaneous lesions.[105,106] A separate cutaneous lesion that is also associated with inflammatory bowel disease, pyoderma gangrenosum, similarly does not necessarily improve upon bowel resection.[107]

7.1 Summary and Recommendations

Because gastrointestinal Crohn disease is multifocal, surgical resection of the affected bowel segment(s) does not necessarily signify the complete eradication of disease inflammation. Based on the discordance between skin and gastrointestinal Crohn disease in terms of temporal occurrence and response to therapy, patients with MCD should be continuously screened for gastrointestinal involvement, and vice versa.

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