A 32-year-old Indian man from Gujarat presents with recurrent oral aphthous ulcers, genital ulcers, and a 3-week history of floaters and blurred vision. Fundoscopy reveals the finding marked **A** in the diagram—white perivascular sheathing of retinal vessels with intraretinal hemorrhages. A positive pathergy test and HLA-B51 positivity support the diagnosis of Behçet disease. Which of the following best describes the pathophysiological basis of the structure marked **A**?
A. Occlusive non-granulomatous phlebitis affecting retinal veins, characteristic of Behçet disease vasculitis
B. Lipid-laden macrophage infiltration of vessel walls secondary to diabetic retinopathy
C. Granulomatous inflammation of retinal arteries with caseating necrosis, typical of tuberculosis
D. Immune complex deposition in retinal capillaries causing vasculitis of all vessel sizes equally
Explanation
Why "Occlusive non-granulomatous phlebitis affecting retinal veins, characteristic of Behçet disease vasculitis" is right
The structure marked A—white perivascular sheathing—is the hallmark of occlusive retinal vasculitis in Behçet disease. The EULAR 2018 and AAO BCSC 2024 guidelines emphasize that Behçet ocular involvement is characterized by a non-granulomatous panuveitis with predominantly VENOUS involvement (phlebitis). The perivascular white sheathing represents inflammatory infiltrate around retinal veins, vessel wall edema, and endothelial proliferation—the defining feature of Behçet retinal vasculitis. This venous predominance distinguishes Behçet from other causes of uveitis and is critical for diagnosis and prognosis.
Why each distractor is wrong
Granulomatous inflammation of retinal arteries with caseating necrosis, typical of tuberculosis: Behçet disease is explicitly non-granulomatous; granulomatous inflammation and caseation are features of tuberculosis and sarcoidosis, not Behçet. Additionally, Behçet affects veins predominantly, not arteries.
Immune complex deposition in retinal capillaries causing vasculitis of all vessel sizes equally: While Behçet is a systemic vasculitis affecting vessels of all sizes, the ocular manifestation shows a characteristic predilection for veins over arteries and capillaries. Immune complex deposition is not the primary mechanism; the vasculitis is mediated by T-cell infiltration and TNF-alpha dysregulation.
Lipid-laden macrophage infiltration of vessel walls secondary to diabetic retinopathy: This describes lipid exudates and hard exudates seen in diabetic retinopathy, not the inflammatory vasculitis of Behçet disease. Diabetic retinopathy does not produce perivascular sheathing or the aggressive panuveitis seen in Behçet.
High-YieldNEET PG
Behçet retinal vasculitis is non-granulomatous, predominantly VENOUS (phlebitis), and explosive—requiring urgent systemic immunosuppression and anti-TNF biologics (infliximab, adalimumab) to prevent blindness.
