Analysis of clinical and pathological characteristics of retroperitoneal paraganglioma and associated prognostic factors

Abstract Background and Objectives The aim of this study is to explore the long‐term prognostic risk factors associated with patients diagnosed with retroperitoneal paraganglioma (RPGL) and examine their clinical and pathological characteristics. Methods Expressions of biomarkers were identified using immunohistochemistry (IHC) and case databases were retrospectively searched. Survival analysis was performed using Kaplan‐Meier and Cox risk regression to identify the factors that influence the postoperative progression‐free survival of patients with RPGL. Results A total of 105 patients, most of whom had tumors situated in the paraaortic region, and whose average tumor size was 8.6 cm, were enrolled in this study. The average follow‐up duration was 51 months, with a mortality rate of 19% and a recurrence and metastasis rate of 41.9%. Tumors were assessed using the modified Grading system for Adrenal Pheochromocytoma and Paraganglioma (GAPP), and SDHB, S‐100, and Ki‐67 were stained using IHC in all cases. Out of the total cases examined, negative in SDHB expression were observed in 18.1% of cases, S‐100 expression was negative in 36.2% of cases, and endovascular tumor enboluswas present in approximately 25.7% of cases. The results of the univariate analysis indicated that several factors significantly influenced the progression‐free survival of patients with PGL as follow: maximum tumor diameter (>5.5 cm), tumor morphological features, tumor grading (modified GAPP score > 6), SDHB negative, S‐100 negative, and expression of proliferation index Ki‐67 (>3%) ( X 2 = 4.217−27.420, p < 0.05). The results of the multivariate analysis indicated that negative of S‐100 ( p = 0.021) and SDHB ( p = 0.038), as well as intravascular tumor thrombus ( p = 0.047) expression were independent risk factors for progression‐free survival in patients. Conclusion RPGL is characterized by diverse biological features and an elevated susceptibility to both recurrence and metastasis. Both SDHB and S‐100 can be employed as traditional IHC indicators to predict the metastatic risk of PGL, whereas the tumor histomorphology‐endovascular tumor enbolus assists in determining the metastasis risk of RPGL.