BACKGROUND: Over recent decades, both the incidence and prevalence of chronic 
inflammatory bowel disease have continued to rise in industrialized countries; 
the disease is frequently associated with extracutaneous involvement and 
comorbidity.
OBJECTIVES: The purpose of this work was to investigate the frequency and 
specificity of mucocutaneous manifestations in Crohn's disease (CD) and 
ulcerative colitis (UC).
MATERIALS AND METHODS: An extensive search in peer-reviewed journals via PubMed 
was performed; presented is a summary and analysis of various studies and data, 
including data of patients treated at our department.
RESULTS: CD and UC are frequently associated with mucocutaneous symptoms; 
however, primary/specific disease-associations are exclusively seen in CD 
patients. These include peri-anal and -stomal fistulas and ulcerations, 
"metastatic" Crohn's disease as well as oral granulomatous disease. Moreover, in 
both CD and UC, there occur several other inflammatory skin conditions such as 
erythema nodosum, pyoderma gangrenosum, hidradenitis suppurativa, chronic oral 
aphthous disease, Sweet syndrome, pyostomatitis vegetans, and bowel-associated 
dermatosis-arthritis syndrome. Malnutrition syndromes (zinc and vitamin 
deficiencies) are only rarely observed.
CONCLUSION: On skin and oral/genital mucous membranes various different 
inflammatory manifestations may be observed during the course of CD or UC. 
However, most data about a direct pathogenic relationship of the 
gastrointestinal and dermatologic disorders are quite heterogeneous or even 
contradictory. Nevertheless, knowledge of these conditions and their possible 
association with CD and UC could be crucial for early diagnosis and initiation 
of an appropriate therapy and thus be essential to prevent secondary tissue 
damage.