What is Perianal Crohn's Disease?

Perianal Crohn's disease is characterized by skin lesions such as anal skin tags, anal abscess, as well as anal canal lesions such as perianal abscesses, fistulas, and fissures - all these symptoms of perianal Crohn's disease and colitis is fully described below.

Perianal disease is more common in patients with colitis and ileocolitis than in small-bowel disease. In one-third of individuals, perianal disease precedes the onset of symptomatic intestinal disease.

In other words, perianal afflictions often come before Crohn's disease or ulcerative colitis is present.

The original description of Crohn's disease did not describe perianal lesions. It wasn't until 1938 that Penner and Crohn described the presence of a perianal fistula in a patient with Crohn's disease.

There is strong evidence for a genetic contribution to perianal Crohn's disease. That perianal disease is a distinct type of Crohn's disease is supported by the recent identification of a susceptibility locus on chromosome 5.

Above is a diagram of a gene believed to be responsible for Crohn's disease. Picture courtesy of Samir.

How Common Is Perianal Crohn's Disease?

Perianal disease is a common complication of Crohn's disease in children and adolescents, females and males. Of 325 Crohn's patients, 200 (62%) developed perianal disease. i In 64 to 68 percent of patients with Crohn's disease perianal complication occurs at the same time or after the diagnosis of intestinal disease. Williams reported that 74 percent of these patients develop perianal lesions within 10 years of diagnosis of intestinal disease.

The more distal the bowel involvement, the greater the prevalence of perianal disease. Thus, perianal disease is more common in patients with colitis and ileocolitis than in small-bowel disease. This was reported by Bergstrand et al who found that 92 percent of patients with rectal disease developed perianal fistula.

Crohn's disease shows a peak incidence in females during their reproductive years. Thus, a high percentage will have active or new onset perianal disease during pregnancy. Perianal disease is usually an indication for caesarean section.

What Are the Symptoms of Perianal Crohn's Disease?

Perianal discomfort is a sign of perianal Crohn's disease. Itchiness or pain around the anus, the external opening of the rectum, may be suggestive of inflammation, fistulization or abscess around the anal area or anal fissure.

The severity of perianal Crohn's disease depends on the severity of the nonperianal disease. In other words, generally, the worse the diarrhea, the more symptomatic the perianal disease.

In a series of 356 Crohn's disease patients, Galandiuk et al. noted that more than 1 perianal fistula was the most common type of perianal disease (87%).ii This was followed in frequency by fissure (44%) and anal-canal stricture (37%).

In another study of patients with perianal Crohn's disease, anal skin tags were present in 35% of patients, fissures in 51%, fistulas in 15%, and abscesses in 13%.iii

Anal Abscess

An abscess is a pocket of pus near the intestine caused by infection from bacteria. This pocket of infection requires drainage either through a catheter inserted by a radiologist or a special drain that is surgically inserted.

An abscess causes tenderness, swelling, and pain. These symptoms disappear when the abscess is drained. Individuals may also complain of fever, chills, and general weakness or fatigue.

Whenever the physician finds an abscess, and especially a fistula, further tests are needed to be sure Crohn's disease is not present. Anal abscess is present in 13% of Crohn's patients.iv

Anal Fissure

This is where I believe the anal fissure is, as it appears to be a small break in the skin's surface. The other posibility is directly down where the blood is, but I can't see an actual tear there.

A fissure is a small cut or crack in the lining of the mucous membrane of the anus (Photo picture of anal fissure is left). The anal fissure may be induced by a hard bowel movement or straining at stool. Fissures constitute 21 to 35 percent of perianal lesions. They are often bluish in appearance and painless, but can cause excrutiating pain if the skin is stretched. Fissures are most commonly located posteriorly (41%), although multiple fissures can occur at other sites.

Anal fissure is present in approximately 51% of patients with Crohn's disease.v An abscess or fistula can subsequently develop in 26 percent of individuals with a fissure.

Anal Fistulas

Anal fistulas are most common in people with Crohn's disease.vi

In Crohn's disease sores or ulcers develop within the intestinal tract. Sometimes these deep ulcers turn into tracts / tunnels—called fistulas—that connect via the hole different parts of the intestine. But fistulas may also tunnel into surrounding tissues such as the bladder, vagina, or skin around the anus (Figure 2, right).

These holes typically spread the infection that creates them, and life-threatening conditions such as peritonitis (inflammation of the lining of the abdomen) may occur.

Anal fistulas develop in the presence of inflammation and infection and often drain pus or liquid which can soil or stain clothing (Figure 2, left). Often a draining fistula is not painful but it can irritate the skin around it. Fistulas can be internal, external, or mixed; single of multiple.

If the fistula is small, antibiotics may be sufficient to heal it. Large or multiple fistulas, on the other hand, may signal the need for surgery, particularly if they are accompanied by fairly persistent symptoms, such as fever or abdominal pain.

Often a fistula forms an abscess near the intestine which requires drainage. This can be done with a seton – a length of suture material looped through the fistula which keeps it open and allows pus to drain out.

Usually when an individual presents with a fistula, flexible sigmoidoscopic examination is warranted to evaluate the mucosa of the distal colon for signs of Crohn's disease. The index of suspicion for Crohn's disease is increased by a history of episodes of diarrhea, abdominal cramping, weight loss, and the appearance, location and multiplicity of fistulas.

Anal Skin Tags and Hemorrhoids

Anal skin tags, also called Crohn's skin tags, frequently occur in Crohn's disease while hemorrhoids occur infrequently; only 0.04 percent of 20 patients with hemorrhoids were noted to have Crohn's disease over a 41 year period.vii

Mark, presumably his alias name, donated this photo of his anal skin tags, to me to raise awareness in the hope that a cure for the skin tags could be found.  Mark suffers from Crohns Disease, a disease known for causing skin tags around the anus, and is deeply distressed by this symptom, because of the way it makes him look. It's always important to realise that people who suffer from Crohn's disease are people with feelings and emotions. Although doctors may class this symptom as of no real health concern in and of itself, from a psychologists perspective, such symptoms of Crohn's disease can be more debilitating than the disease itself.

Anal skin tags have been classified into 2 types:

1. Raised, broad or narrow, and painless, often referred to as “elephant ears”, as seen in the photo above.

2. Edematous, often cyanotic, tender or not, and typically arising from a healed anal fissure, or hemorrhoid.

Anal skin tags are more commonly found in association with Crohn's disease (75.4%) compared to patients with ulcerative colitis (24.6%) and are more common in the presence of disease limited to the colon as compared to disease elsewhere in the bowel.viii

Anal skin tags are diagnostic of Crohn's disease especially in young people with diarrhea, abdominal pain, and/or growth retardation.

Anal skin tags are generally asymptomatic and often are the remnants of previously thrombosed external hemorrhoids. When tags are symptomatic, as a result of itching or hygienic problems, they can be removed. Local anesthetic is injected and the area is excised and then sutured or left to heal. But remember that any surgery below the dentate line causes considerable postoperative pain. Moreover, in patients with Crohn's disease, conservative management is advised because of the post-operative risk of poor wound healing, anorectal stenosis and the potential need for subsequent proctectomy.

Other Symptoms of Perianal Crohn's Disease

Perianal Crohn's disease can be extremely debilitating.

Fecal incontinence may accompany perianal Crohn's disease. Perianal pain and fecal soiling greatly diminish an individual's quality of life.

Perianal involvement can lead to social isolation because individuals have urgency, frequency, stool incontinence that can be related to either the disease itself of other complications.

At the other end of the gastrointestinal tract, the mouth may be affected by non-healing sores called aphthous ulcers. The stomach and esophagus are rarely involved in Crohn's disease. However, if they are, this can cause difficulty swallowing, upper abdominal pain, and vomiting.

Other symptoms include pain, soiling, sleep disruption, sexual dysfunction, and sepsis.

How is Perianal Crohn's Disease Diagnosed?

The diagnosis of perianal Crohn's disease necessitates radiological imaging of the gastrointestinal tract. Most radiologists perform magnetic resonance imaging (MRI) under anesthesia which is particularly useful in the identification of undiagnosed fistula and in monitoring the effects of treatment.

There are a number of questionnaires that are used to determine a patient's quality of life with perianal disease.

Does Perianal Crohn's Disease Cause Cancer?

Perianal disease is associated with colorectal cancer. There is an increased risk of developing colorectal cancer in patients with perianal Crohn's disease.ix

The earlier in your life that you develop Crohn's disease, the greater your risk for developing perianal complications and the greater your risk for developing colorectal cancer. Also known as fistula-related cancer, many people with Crohn's disease are surprised to learn that the condition is present after self-treating hemorrhoids during a flare-up.

Adenocarcinoma mandates proctectomy (removal of the colon). Squamous carcinoma may be considered for chemo-radiotherapy although proctectomy is usually the preferred option.

References for Perianal Crohn's Disease

Written by Dr. Kirchgessner, edited by Donald Urquhart