A 28-year-old man of Turkish descent presents to the clinic with a 4-day history of painful sores in his mouth. He reports that he has had similar episodes multiple times a year for the past three years. He also mentions a painful lesion on his scrotum that appeared yesterday and a 2-week history of blurry vision and redness in his right eye. On physical examination, there are three shallow, well-circumscribed ulcers with erythematous borders on the buccal mucosa and a 1-cm ulcer on the posterior scrotum. Ophthalmologic evaluation with a slit-lamp exam reveals cells and flare in the anterior chamber. A skin prick test performed in the office results in the formation of a sterile pustule 24 hours later.
Which of the following is the most likely diagnosis?
The correct answer is:
A) Behcet syndrome
Behcet syndrome is a chronic, relapsing systemic vasculitis of unknown etiology, though it is strongly associated with the HLA-B51 allele. It is most common in populations along in the Middle East, Central Asia, and East Asia. The hallmark of the disease is recurrent, painful aphthous-like oral ulcers occurring at least three times in a year. To meet diagnostic criteria, patients must also have at least two of the following: recurrent genital ulcers (which are typically deeper and more prone to scarring than oral ulcers), ocular lesions (such as anterior or posterior uveitis), or skin lesions (such as erythema nodosum or acneiform nodules). The patient also demonstrates a positive pathergy test, which is a highly specific finding where a minor skin trauma like a needle prick induces the formation of a sterile papule or pustule within 24–48 hours.
Answer choice B: Crohn disease, is incorrect. While Crohn disease can cause oral aphthous ulcers and uveitis, it is primarily a gastrointestinal disorder characterized by abdominal pain, chronic diarrhea, and weight loss. It does not typically cause recurrent genital ulcers or a positive pathergy test.
Answer choice C: Herpes simplex virus (HSV) infection, is incorrect. Herpes simplex virus (HSV) can cause recurrent oral and genital ulcers. However, HSV lesions typically begin as clusters of small vesicles on an erythematous base that later rupture into ulcers. It would not explain the patient's uveitis or the positive pathergy test.
Answer choice D: Reactive arthritis, is incorrect. Reactive arthritis presents with a triad of "can't see (uveitis/conjunctivitis), can't pee (urethritis), and can't climb a tree (arthritis)." While it shares the ocular findings, the oral lesions in reactive arthritis (circinate balanitis or painless mouth ulcers) are typically painless, and it does not feature recurrent, painful genital ulcers or pathergy.
Answer choice E: Systemic lupus erythematosus (SLE), is incorrect. Systemic lupus erythematosus (SLE) can cause oral ulcers, but they are classically painless. While SLE can cause ocular and skin manifestations, it is characterized by other systemic findings such as malar rash, photosensitivity, and hematologic abnormalities (e.g., cytopenias) that are absent in this patient.
Key Learning Point
Behcet syndrome is a multi-system vasculitis characterized by the triad of recurrent oral ulcers, genital ulcers, and uveitis. It is associated with HLA-B51 and a positive pathergy test. The disease can involve both small and large vessels and can lead to serious complications such as blindness due to retinal vasculitis)or central nervous system involvement.
