Diagnosis: Behçet's Disease
This patient has Behçet's disease, characterized by the classic triad of recurrent oral ulcers, genital ulcers, and uveitis with anterior chamber inflammation. The negative Tzanck smear excludes herpes simplex virus infection, which is a critical differential diagnosis in patients presenting with mucocutaneous ulcers and ocular inflammation 1.
Clinical Reasoning
Diagnostic Criteria Met
The patient presents with the hallmark features of Behçet's disease:
- Recurrent oral ulcers: Multiple ulcers on the oral mucosa represent the most consistent feature of Behçet's disease
- Genital ulcers: Three symmetrical shallow scrotal ulcers are characteristic of Behçet's disease
- Ocular inflammation: Anterior uveitis with cell and flare in the anterior chamber, presenting with the classic symptoms of eye pain, blurred vision, and photophobia 2, 3
Key Differentiating Features
The negative Tzanck smear is crucial because it excludes herpes simplex virus (HSV) infection, which can present with similar mucocutaneous ulcers and uveitis 1. Multinucleated giant cells on Tzanck smear would indicate HSV infection, making this test essential in the diagnostic workup.
The symmetrical distribution of genital ulcers and their shallow appearance are more consistent with Behçet's disease than infectious etiologies 1.
Critical Diagnostic Considerations
Mandatory Exclusions Before Confirming Behçet's Disease
While the clinical presentation strongly suggests Behçet's disease, you must exclude sexually transmitted infections, particularly syphilis and HIV, as these can perfectly mimic Behçet's disease with oral ulcers, genital ulcers, and panuveitis 1. The research evidence demonstrates that misdiagnosis occurs when clinicians fail to screen for these infections, leading to suboptimal treatment responses to steroids 1.
Essential laboratory screening includes:
- Syphilis serology (RPR/VDRL and treponemal testing)
- HIV testing
- Complete blood count and inflammatory markers (ESR, CRP)
- HLA-B27 testing (to exclude spondyloarthropathy-associated uveitis) 4
Other Important Differentials to Consider
Inflammatory bowel disease (IBD) can present with oral ulcers and anterior uveitis, though genital ulcers are not typical 5, 6. However, uveitis in IBD is frequently bilateral and insidious in onset, and typically occurs in patients with known bowel disease 5.
Ankylosing spondylitis causes acute anterior uveitis in up to 40% of patients, but the uveitis is typically unilateral, acute, and recurrent rather than presenting with the mucocutaneous features seen here 5.
Management Approach
Urgent Ophthalmologic Referral Required
This patient requires immediate referral to an ophthalmologist with expertise in ocular inflammatory disease because anterior chamber inflammation can progress to permanent vision loss if untreated 5, 2, 6. The presence of moderate to severe eye pain, photophobia, and blurred vision are red flags mandating urgent evaluation 2, 6, 7.
Initial Treatment Strategy
Topical corticosteroids and cycloplegics are first-line treatment for anterior uveitis 6. The ophthalmologist will use slit-lamp examination to confirm the diagnosis and assess disease severity 5, 6.
Systemic therapy may be required if:
- Uveitis is refractory to topical treatment
- There are frequent relapses
- Sight-threatening complications develop 6
For Behçet's disease specifically, the guidelines note that uveitis can be independent of other disease manifestations and may require aggressive systemic immunosuppression 5.
Critical Pitfalls to Avoid
Do not assume Behçet's disease without excluding infectious mimics, particularly in patients with risk factors for sexually transmitted infections 1. Syphilis-associated uveitis has a good prognosis with antibiotic treatment (92% resolution rate), whereas misdiagnosis leads to inappropriate immunosuppression 1.
Do not delay ophthalmologic referral while completing the diagnostic workup—vision-threatening complications can develop rapidly, and topical treatment should be initiated promptly 2, 6.