# Appendicular Neuroendocrine Tumours: An Unusual Cause of Hydronephrosis

## TL;DR

A rare case of a neuroendocrine tumor in the appendix causing hydronephrosis is reported, highlighting the difficulty in diagnosing such uncommon tumors.

## Contribution

The paper presents a rare clinical case of an appendicular neuroendocrine tumor invading the ureter, emphasizing diagnostic challenges.

## Key findings

- A 30-year-old woman was diagnosed with a neuroendocrine tumor in the appendix that had invaded the ureter.
- The tumor was confirmed using immunohistochemical staining for chromogranin and synaptophysin.
- The case underscores the need for thorough histological evaluation in ambiguous diagnoses.

## Abstract

Although neuroendocrine tumours (NETs) are predominantly located in the gastrointestinal tract, pancreas, and lungs, they can also occur in uncommon places such as the biliary system, prostate, breast, head, neck, and even the spinal cord. We present the case of a 30-year-old woman who was referred to the urology clinic for right ureterohydronephrosis. Because the contrast-enhanced CT scan did not show signs of kidney stones or an upper urothelial tract cell carcinoma and was combined with renal scintigraphy, the kidney was not functional, and a left nephrectomy was performed. During the surgery, it was observed that the appendix was attached to the ureter by a tiny tumour. In addition, an appendectomy was also conducted. The pathological test indicated the presence of a NET that had invaded the ureter. The diagnosis was confirmed by immunohistochemical staining. The tissue has been positive for chromogranin and synaptophysin staining. Our work highlights the infrequency and difficulty of diagnosing NETs that invade the ureter. Conducting a thorough histological evaluation in patients with uncertain histopathological diagnoses is essential.