Is It Behcet’s? Review Course Offers Diagnosis Tips

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WASHINGTON, D.C.—Behçet’s disease (BD) is not a common condition, but we frequently receive referrals to evaluate for it in rheumatology clinics because a patient has oral or genital ulcers. So what’s Behçet’s and what’s not? How can we tell the difference?

At the ACR Convergence 2024 Review Course, Johannes Nowatzky, MD, director, New York University Langone Behçet’s Disease & Ocular Rheumatology Programs, Saul J. Farber associate professor of medicine, associate professor of pathology, New York University Grossman School of Medicine, gave an exceptional talk on the differential for oral ulcers and more.

Dr. Nowatzky

Not All Oral Ulcers Are Behçet’s

To illustrate this point, Dr. Nowatzky kicked off his talk with nine riveting cases, all of which included oral and/or genital ulcers. Only one of eight patients had BD. The others had mucosal erythema multiforme, Crohn’s disease, ankylosing spondylitis, sarcoidosis and other conditions.

So which ulcers are BD and which aren’t? Oral ulcers are not specific, but are generally perceived to be mandatory for a diagnosis of BD. “The trick is to understand what type of lesions really count and what the clinical context is. You can’t make a diagnosis of BD from looking at oral ulcers alone because recurrent aphthous stomatitis (RAS) looks exactly the same. However, you can often rule out BD by looking at the appearance of a mucosal lesion that is not an apthuous oral ulcer.”¹

When trying to identify aphthous oral ulcers, three features can help. Ask yourself:

• Is there a yellow-white homogenous base?
• Is there a red halo around the outside of the lesion?
• Is it round or oval?

If the answer to all three questions is yes, then it could be an aphthous ulcer, which still has a differential diagnosis. If not, think of something other than BD and extend your differential diagnosis even further.

Not All Oral & Genital Ulcers Are Behçet’s

What about a patient with aphthous oral and genital ulcers? Definitely Behçet’s, right? Nope, not always. Oral and genital ulcers without extra-mucosal findings are better called complex aphthosis, a combination of RAS and genital ulcers. Menstruation, vitamin deficiency, zinc and iron deficiency, inflammatory bowel diseases and celiac disease are the most common causes of complex aphthosis in the U.S. BD is much further down the list in most practice settings here, and extra-mucosal manifestations should be present.