Primary adenocarcinoma of the renal pelvis: An uncommon tumor, a case report

Primary adenocarcinoma of the renal pelvis is a rare and unique malignancy, representing a small fraction of renal cancers and posing significant diagnostic challenges due to its unusual presentation and similarity in symptoms to more common excretory tract disorders. This case emphasizes the importance of distinguishing this pathology from other renal neoplasms and metastatic adenocarcinomas that originate in the digestive tract.

We report the case of a 34-year-old man with no significant medical history who presented persistent lower back pain but no hematuria, which is atypical for renal pathologies. Initial imaging identified a 30 × 14 mm enhancement mass in the right renal pelvis. Surgical intervention was performed through right nephroureterectomy, including excision of the bladder cuff. Histopathological examination confirmed the diagnosis of primary intestinal-type adenocarcinoma of the renal pelvis, characterized by necrotic carcinomatous proliferation with varying architectural patterns and occasional signet ring cells.

The diagnosis of primary renal pelvis adenocarcinoma is complicated by its nonspecific symptomatology and the potential for misdiagnosis as a more common urothelial carcinoma or a metastatic digestive-origin adenocarcinoma. Immunohistochemical staining supported a primary rather than metastatic digestive tract origin. This case underscores the need for a comprehensive diagnostic approach, including advanced imaging and meticulous histopathological analysis, to effectively differentiate this rare entity from other neoplasms.

This case highlights the diagnostic complexities and the critical need to be aware among clinicians about rare renal cancers such as primary adenocarcinoma of the renal pelvis. It also stresses the importance of interdisciplinary collaboration in the diagnosis and management of such rare cases, improving our understanding and requiring timely and accurate treatment.