Clinical Characteristics and Surgical Outcomes of Retroperitoneal Unicentric Castleman Disease: A Single-Center Retrospective Study

Objective: We aimed to characterize the inflammatory and complication profiles of patients with retroperitoneal unicentric Castleman disease (UCD), compare the clinical features of UCD with an MCD-like inflammatory state (UCD-MIS) and non-MIS cases, and describe treatment patterns and follow-up outcomes.
Materials and methods: We retrospectively analyzed 75 patients with retroperitoneal UCD treated at our institution between 2000 and 2025, focusing on inflammatory phenotypes, severe complications, surgical extent, and follow-up outcomes.
Results: UCD-MIS was identified in 20 patients (26.7%). Paraneoplastic pemphigus (PNP) occurred in 9 patients (12.0%), bronchiolitis obliterans (BO) in 8 (10.7%), and amyloid A (AA) amyloidosis in 2 (2.7%). Patients with UCD-MIS more frequently had PNP (35.0% vs. 3.6%; FDR-adjusted P = 0.004) and BO (25.0% vs. 5.5%; FDR-adjusted P = 0.042) than those without MIS. For treatment, 61 patients underwent surgery, including 57 complete resections. During a median follow-up of 60.8 months (range, 6.1-266.2 months), two deaths occurred. Both patients had PNP and met the criteria for UCDMIS, and one also had BO. Neither patient had undergone surgical excision of the UCD lesion. The small number of deaths precluded between-group survival comparisons.
Conclusion: Comprehensive screening for complications is essential in retroperitoneal UCD, and complete surgical excision remains the cornerstone of therapy when technically feasible.

Keywords: surgery, Castleman disease, UCD-MIS, retrospective analysis