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PubMed This is a summary of 22 peer-reviewed journal articles Updated
Gastroenterology · Behçet's Disease

What is the Difference Between Behçet's and Crohn's?

At a Glance

Behçet's disease and Crohn's disease share similar symptoms like painful mouth and intestinal ulcers. Doctors tell them apart by identifying deep, round ulcers and inflamed blood vessels in Behçet's, versus irregular cobblestone ulcers and granulomas in Crohn's.

In this answer

7 sections

01

Differences in Mouth Ulcers

02

Clues from Your Colonoscopy

03

What Biopsies Reveal

04

Symptoms Outside the Gut

05

Specialized Tests

06

Managing Symptoms While You Wait

07

Quick Comparison Summary

It is incredibly frustrating to suffer from severe symptoms without having a clear name for your condition. Behçet’s disease and Crohn’s disease are both driven by an overactive immune system, and they share many overlapping symptoms—which makes them very difficult to tell apart [1][2]. Both diseases can cause severe, painful ulcers in the mouth, stomach, and intestines, leading to similar digestive symptoms [3][4].

Because the conditions look so similar, doctors use a combination of clues—like the shape of your ulcers, biopsy results, and specific symptoms outside your gut—to make the right diagnosis.

Differences in Mouth Ulcers

While both conditions can cause sores in the mouth, the ulcers often behave differently:

  • In Behçet’s disease: Recurrent, painful mouth ulcers (aphthous ulcers) are a core feature of the disease. They often come and go in flares and can be shallow or deep [1][5].
  • In Crohn’s disease: Mouth ulcers can occur, but they are often more persistent, irregular, or associated with a specific type of swelling in the lips or face (orofacial granulomatosis) [1][5].

Clues from Your Colonoscopy

During a colonoscopy, your doctor looks at the shape and pattern of the ulcers in your intestines. While both diseases commonly affect the same area of the gut (the ileocecal region, where the small intestine meets the large intestine) [3][6], the ulcers tend to look differently:

  • In Behçet’s disease: Ulcers usually appear as discrete, deep, round, or oval-shaped “punched-out” holes [3][7][4].
  • In Crohn’s disease: Ulcers are often irregular, long, and snake-like (longitudinal), sometimes giving the surrounding intestinal lining a bumpy “cobblestone” appearance [3][7].

What Biopsies Reveal

When your doctor takes a tiny tissue sample (biopsy) during your colonoscopy, they look at it under a microscope to see how the inflammation is acting [3].

  • Behçet’s disease is primarily a type of vasculitis, meaning the inflammation centers around your blood vessels [8][9]. Biopsies often show inflamed or swollen veins (thrombophlebitis) [9][10].
  • Crohn’s disease often causes a specific type of immune cell clustering called granulomas, and the inflammation usually spreads through the entire thickness of the intestinal wall [9][11].

Symptoms Outside the Gut

Doctors also look for symptoms outside your digestive system (called extraintestinal manifestations) to tell the diseases apart [3][4].

  • Genital Ulcers: Recurrent genital sores are a hallmark of Behçet’s disease but are very rare in Crohn’s disease [12][13].
  • Eye Inflammation: Both conditions can cause eye problems, but severe, full-eye inflammation called panuveitis is a classic sign of Behçet’s [13][14].
  • Blood Vessel Issues: The presence of blood clots in the veins (venous thrombosis) or bulging arteries (aneurysms) points strongly toward Behçet’s [4].

Specialized Tests

If your symptoms and colonoscopy leave your doctor unsure, they might use specific tests to help confirm a diagnosis:

  • The Pathergy Test: This is a simple skin prick test using a sterile needle. If a small red bump or blister forms a day or two later, the test is positive. This overreactive skin response is a key feature of Behçet’s disease, though it is not positive in everyone who has the condition [15][16][17].
  • Genetic and Blood Markers: Testing positive for a genetic marker called HLA-B51 can support a Behçet’s diagnosis [18]. Additionally, specialized blood tests can provide clues; for example, testing negative for specific antibodies known as ASCA (Anti-Saccharomyces cerevisiae antibodies) favors a diagnosis of Behçet’s over Crohn’s [19][20].

Managing Symptoms While You Wait

Waiting for a definitive diagnosis can be daunting. Fortunately, while doctors are working to tell the two diseases apart, there are treatments that work for both. For example, certain advanced biologic medications that target inflammation (such as anti-TNF-alpha agents like infliximab) have been shown to be effective and safe for treating severe intestinal ulcers, even when it is still ambiguous whether you have Behçet’s or Crohn’s [21][22].

Quick Comparison Summary

Feature Behçet’s Disease Crohn’s Disease
Intestinal Ulcer Shape Deep, round, or oval (“punched-out”) [3] Long, irregular, or “cobblestone” [3]
Mouth Ulcers Recurrent, painful, aphthous-like [1] Persistent, irregular [5]
Biopsy Results Inflamed blood vessels (vasculitis) [8] Clustered immune cells (granulomas) [11]
Genital Ulcers Very common [12] Rare [13]
Pathergy Test Often positive [15] Rarely positive [16]
ASCA Blood Test Usually negative [19] Often positive [20]

Common questions in this guide

How do intestinal ulcers differ between Behçet's disease and Crohn's disease?
In Behçet's disease, intestinal ulcers usually appear as discrete, deep, round, or oval-shaped holes, often described as 'punched-out'. In Crohn's disease, the ulcers are typically long and irregular, which can give the intestinal lining a bumpy 'cobblestone' look.
Can an intestinal biopsy tell the difference between Behçet's and Crohn's?
Yes, a biopsy can provide crucial clues. A biopsy for Behçet's disease often shows inflamed blood vessels, indicating vasculitis. In contrast, a biopsy for Crohn's disease typically reveals clusters of immune cells called granulomas and inflammation through the entire intestinal wall.
What is a pathergy test?
The pathergy test is a skin prick test using a sterile needle. If a small red bump or blister forms a day or two later, the test is positive. This overreactive skin response is a key feature used to help diagnose Behçet's disease.
Do both conditions cause genital ulcers?
While both conditions cause mouth and intestinal ulcers, recurrent genital sores are a hallmark symptom of Behçet's disease. Genital ulcers are very rare in people with Crohn's disease.
What blood tests help distinguish Behçet's from Crohn's?
Doctors may check for the HLA-B51 genetic marker, which supports a Behçet's diagnosis. They may also look for ASCA antibodies; testing negative for ASCA favors Behçet's, while testing positive is more common in Crohn's disease.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Based on my colonoscopy images, do my ulcers look more 'punched-out' or 'cobblestone'?
  2. 2.Did my intestinal biopsy results show any signs of granulomas or inflamed blood vessels (vasculitis)?
  3. 3.Should we perform a pathergy test to see how my skin reacts to a needle prick?
  4. 4.Given my specific symptoms, would it be helpful to run blood tests for the HLA-B51 genetic marker or ASCA antibodies?
  5. 5.While we are waiting to confirm a final diagnosis, what treatment options are available to help manage my pain and inflammation?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

Related questions

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References

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This page is for informational purposes only and does not replace professional medical advice. Always consult your gastroenterologist or rheumatologist for a proper diagnosis and treatment plan.

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