Inflammatory myofibroblastic tumor of the right renal pelvis: A case report

Abstract

Inflammatory myofibroblastic tumor(IMT) is an uncommon soft tissue neoplasm rarely reported in the urinary tract. A 54-year-old male presented to our institution with low back and abdominal pain, hematuria, and lower urinary tract symptoms for 2 months. We performed abdominal contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), which showed a mass in the right renal pelvis-inferior calyx. Then, we performed the laparoscopic radical nephroureterectomy.

1 Introduction

IMT is a rare mesenchymal tumor, commonly found in the lungs and rarely in the urinary tract, especially the renal pelvis. Initially considered a benign inflammatory process, IMT is now recognized for its potential malignancy due to chromosomal abnormalities in the p21-23 region of chromosome 2. Herein, we report a case of a patient with right renal pelvis IMT who underwent laparoscopic radical nephroureterectomy.

2 Case report

In April 2023, a 54-year-old male presented to our institution with low back and abdominal pain, hematuria, and lower urinary tract symptoms for 2 months. He denied malignancy, abdominal trauma, and a history of smoking, and a routine physical examination revealed no significant abnormalities. His initial urinalysis indicated elevated leukocytes and significant occult blood, though other laboratory values were normal. To clarify the source of hematuria and pain, we performed abdominal contrast-enhanced computed tomography (CT), which showed a mass of approximately 1.1 × 1.2 × 2.2 cm in the right renal pelvis-inferior calyx, with heterogeneous enhancement in the arterial phase, slightly diminished in the venous phase, and the renal pelvis showing a filling defect in the delayed phase( Fig. 1 A and B). Considering a high probability of a malignant tumor of the renal pelvis, we performed a urine cytology, and the results were negative. Magnetic resonance imaging (MRI) was then performed, and the results indicated a soft-tissue mass in the right renal pelvis-inferior calyx with irregular morphology, weak enhancement, and diffusion-limited in the diffusion-weighted imaging (DWI) ( Fig. 1 C and D), which was consistent with the CT diagnosis.