Renal neuroendocrine tumors

Area of Science:

• Oncology
• Pathology
• Urology

Background:

• Neuroendocrine tumors (NETs) are a diverse group of neoplasms with varying differentiation and behavior.
• Primary NETs of the kidney, including carcinoid tumors, small cell carcinoma (SCC), and large cell neuroendocrine carcinoma (LCNEC), are exceptionally rare.

Purpose of the Study:

• To review the clinicopathologic features of renal NETs.
• To analyze reported cases of renal NETs in the worldwide literature.

Main Methods:

• Retrospective review of renal NETs diagnosed at a single institution.
• Comprehensive literature search for all reported cases of renal NETs.

Main Results:

• Eighty renal NETs have been documented globally, with nine from the study institution.
• Distinguishing renal NETs from common renal neoplasms can be challenging due to overlapping features.
• Immunohistochemical markers (synaptophysin, chromogranin) are crucial for diagnosis.
• Renal carcinoids show variable clinical courses, while SCC and LCNEC typically present with advanced disease and poor outcomes.
• Nephrectomy may be curative for localized disease; advanced cases require multimodal treatment.

Conclusions:

• A range of NETs can occur in the kidney, though rarely.
• Renal carcinoids have a variable prognosis, whereas SCC and LCNEC are associated with poor outcomes.
• Accurate diagnosis, particularly for LCNEC, necessitates awareness of their rarity and judicious use of neuroendocrine markers.