Local Kidney Hyperplasia as an Aberrant Lobule: Complexity of CT-Differential Diagnosis with Clear-Celled Renal Tumor

Report of a clinical case demonstrating aberrant hyperplastic renal lobule. The mass of the lower third of the left kidney revealed in the patient at the residential prophylactic medical examination at an ultrasound. The patient was sent to oncourology hospital with suspected renal tumor for a consultation and possible treatment. The contrast-enhanced MSCT of the abdomen was performed and it revealed soft tissue mass with pronounced and uneven enhancement in the cortico-medullary and parenchymal phase, with the subsequent gradual reduction of enhancement in the excretion phase. This resulted in left kidney resection. A resection of the kidney with tumor formation is performed within safe tissues. Later, taking into the account all clinical-morphological data the removed tumor-like node in the left kidney was characterized as an abnormality in the development of the kidney in the form of an aberrant hyperplastic renal lobule. In general, it can be considered that a correct preoperative and intraoperative diagnosis in this observation was practically difficult and even impossible. That is why the definitive diagnosis was only determined by pathomorphological study of the resected macrosection. This case demonstrates the difficulty of preoperative diagnosing. This clinical case demonstrates the complexity of pre-operative diagnosis of an extremely sparse and rarely described in the world literature anomaly of the development of urogenital system — local kidney hyperplasia. The possibilities of modern diagnostic methods are limited in differential diagnosis of this anomaly with malignant kidney tumors. In this situation we were able to isolate a single indirect sign of local hyperplasia: the prolapse of the medullary layer of the kidney into the formation.