Clinical heterogeneity of ocular Behçet's syndrome versus intestinal Behçet's syndrome: a cross-sectional study from Shanghai Behçet's syndrome database

Background: Behçet's syndrome (BS) is a rare variant vasculitis which can involve the eyes and gastrointestinal systems. However, ocular involvement rarely overlaps with intestinal lesions. This study aimed to compare the clinical characteristics and laboratory parameters of ocular BS and intestinal BS patients in China and analyze the differences between two key phenotypes to verify the heterogeneous conditions in BS patients.

Methods: A retrospective analysis was used to collect the demographic data, clinical characteristics, endoscopic findings, and laboratory parameters from 135 ocular BS and 174 intestinal BS patients. The Mann-Whitney U test and Pearson chi-square or continuity correction was used to analyze the differences between two groups.

Results: Among 916 BS patients enrolled in this study, ocular BS and intestinal BS accounted for 14.74% (135 cases) and 19.00% (174 cases), respectively. Ocular and intestinal involvements overlapped in only 7 cases (0.76%). Male gender (74.8% vs. 51.1%, P=0.00), erythema nodosum (45.9% vs. 32.2%, P=0.01), and vascular involvement (6.7% vs. 1.7%, P=0.03) were more frequent in the ocular BS group compared with the intestinal BS group. On the contrary, hematologic involvement (7.5% vs. 0.0%, P=0.00) and fever (17.8% vs. 4.4%, P=0.00) were more frequent in the intestinal BS group compared with the ocular BS group. Additionally, the inflammation markers including ESR [26.5 (16.0-41.5) vs. 9.0 (5.0-15.0) mm/H, P=0.00], CRP [14.8 (4.8-33.0) vs. 4.1 (1.6-8.3) mg/L, P=0.00], serum amyloid A [27.4 (10.8-92.3) vs. 11.3 (6.0-24.0) mg/L, P=0.00], and interleukin 6 [8.4 (1.7-18.7) vs. 1.7 (1.5-3.2) pg/mL, P=0.00] were higher in the intestinal BS group than those in the ocular BS group, respectively.

Conclusions: Ocular BS was more prevalent in male patients and more likely to manifest with erythema nodosum and vascular involvement, while intestinal BS tends to have fever and hematologic disorders with higher inflammation markers. Ocular BS and intestinal BS are two distinct clinical phenotypes and very rarely overlapped.