Clinicopathologic Features of Renal Neuroendocrine Neoplasms

Abstract Primary renal neuroendocrine tumors (NENs) are a unique and rare type of tumor, with relatively limited research. In our retrospective study, we aimed to comprehensively investigate the clinicopathological features, biological behavior, and prognosis of patients that diagnosed as renal neuroendocrine tumors and treated at our center. Histological evaluations were meticulously conducted on archived diagnostic slides obtained from pathological examinations. Notably, all six cases of primary renal neuroendocrine tumors presented as solitary lesions, with a predilection for the left kidney in the majority (4/6) of cases. In accordance with the latest WHO classification, one case was diagnosed as neuroendocrine carcinoma (NEC), while the remaining five cases were identified as well-differentiated neuroendocrine tumors (NETs). Microscopically, the tumor cells exhibited distinctive organ-like structures. One case demonstrated characteristics of a large cell type, with mitotic images and visible necrosis. All tumor synaptophysin were diffusely stained, although chromogranin and CD56 staining patterns varied. Further molecular investigation using next-generation sequencing (NGS) in one case unveiled copy number amplification of the MCL-1 gene; however, no common molecular changes observed in gastroentero-pancreatic neuroendocrine tumors (GEPNEN), such as VHL, ATRX, and DAXX mutations. The limited knowledge regarding the molecular profile and survival outcomes of primary renal neuroendocrine tumors underscores the necessity for enhanced understanding of their behavior. In the process of clinical diagnosis, an improved awareness and accurate diagnosis are imperative to facilitate optimal treatment strategies for patients.