[The relationship between clinical characteristics and pathological features in patients with...

Objective: To explore the correlation between clinical characteristics and pathological features in patients with pheochromocytoma/paraganglioma (PPGLs). Methods: A case series study. A retrospective analysis was conducted on patients with single and primary PPGLs after postoperative pathological diagnosis who were admitted to Peking Union Medical College Hospital between January 2019 and December 2022. The patients were divided into the Ki-67<3% group and the Ki-67≥3% group with Ki-67 proliferation index of 3% as the threshold. The relationship between clinical and pathological characteristics of PPGLs was analyzed. Results: A total of 399 PPGLs patients were included, with 177 males and 222 females, aged [M(Q₁, Q₃)] 45.0(35.5, 53.0) years. Among them, 226 (56.6%) cases originated from the adrenal gland, while 104 cases (26.1%) from the retroperitoneum. 20.9% (27/129) of the patients were found to harbor germline mutations of susceptibility genes, with SDHB mutations being the most common (10.1%, 13/129). The Ki-67 staining was performed on 302 cases, with a Ki-67 proliferation index [M(Q₁, Q₃)] of 2.0% (1.0%, 3.0%). There were 194 cases in Ki-67<3% group and 108 cases in Ki-67≥3% group. Compared with the patients in Ki-67<3% group, the age of onset in Ki-67≥3% group was younger (P=0.029). Compared with the patients with paragangliomas without SDHB or Cluster 1A-related gene mutations, positive ¹³¹I-meta-iodobenzylguanidine (¹³¹I-MIBG) imaging or negative O-6-methylguanine-DNA methyltransferase (MGMT) immunohistochemistry staining, those with SDHB or Cluster 1A-related gene mutations, negative ¹³¹I-MIBG imaging or positive MGMT immunohistochemistry staining had a higher Ki-67 index (all P<0.05). Compared with adrenal pheochromocytoma, retroperitoneal paragangliomas had a higher proportion of SDHB mutations and a higher proportion of normetanephrine (NMN) secretory types (all P<0.05). Compared with adrenal pheochromocytoma, the maximum diameter of head and neck paraganglioma tumors was smaller [3.0 (1.9, 3.8) cm vs 4.7 (3.4, 6.4) cm, P<0.001] and the proportion of Ki-67≥3% was higher (61.3% vs 33.8%, P=0.007). Conclusions: PPGLs patients with earlier onset age, SDHB or Cluster 1A-related gene mutations, negative ¹³¹I-MIBG imaging, or positive MGMT immunohistochemistry staining tend to have a higher Ki-67 index. Head and neck tumors, though smaller, exhibit a higher proliferation potential.