It's hard to imagine that Crohn's disease and Psoriasis have much in common; one affects the digestive system, the other the skin.

However, the two diseases are similar and there is a significant correlation between the two. If you have Crohn's disease, you should be aware of this link.

Psoriasis is a skin disease that often appears the elbows, knees, scalp and back. The telltale signs of Psoriasis are a red rash with silvery white scales. Psoriasis is associated with other serious health conditions, such as diabetes, heart disease and depression.

Like Crohn's disease, Psoriasis is a chronic condition for which there is no cure. While a definitive cause for the two diseases is still not clear, medical experts suspect stress, diet and genetics play a role in both.

The Relationship

The incidence of Crohn's disease and ulcerative colitis, another Inflammatory Bowel Disease, in people with Psoriasis is higher than those who do not. Furthermore, if a close relative has Psoriasis, you are at greater risk for developing Psoriasis and other immune-related diseases, such as Crohn's. In fact, in a study of 12,502 Psoriasis patients, researchers found they were two-and-a -half times more likely to have Crohn's disease.

Physicians find inflammatory damage in the intestines of people who have active cases of Psoriasis, even in people who have not been diagnosed with inflammatory bowel disease. When studied under a microscope, 40 percent of patients had intestinal inflammation.

Crohn's and Psoriasis are diseases of the immune system. In both, the body's immune system attacks cells in the intestines or skin as if they were foreign objects. 

The diseases share a human gene called Tumor Necrosis Factor-a (TNF-a). TNF-a is present in every type of cell in our body. In response to inflammatory signals, cells secrete TNF-a, which may either cause cells to die or to proliferate rapidly. TNF-a is implicated in many diseases, including Psoriasis and Crohn's.

Drug therapies work by blocking TNF-a receptors so TNF-a cannot bind to cells and trigger inflammation. This explains why drugs developed to treat one disease are also sometimes effective treating other diseases. Physicians may prescribe Inflixambab, an immune suppressant, for example, to treat Crohn's, Psoriasis and rheumatoid arthritis, another inflammatory disease.



Psoriasis in Patients with Crohn's Disease or Ulcerative Colitis.
Source: J Eur Acad Dermatol Venereol  
Date Added:2/27/2009 8:26:00 AM

J Am Acad Dermatol 2003; 48 (6): pages 805-21

Journal of Rheumatology 2000; 27 (5): pages 1241-6

Ann Univ Mariae Curie Sklodowska (Med) 1998; 53: pages 187-194