Primary adult renal pelvic soft tissue giant cell tumor: A rare case report

Pyelonephric giant cell tumor of soft tissue represents an exceptionally uncommon neoplasm of the urinary tract with limited malignant potential. It typically follows a benign clinical trajectory, with distant metastases occurring infrequently; reports of aggressive disease culminating in lethal multiorgan dissemination are exceedingly rare. The present case seeks to augment the clinical dataset and elucidate the features of its malignant transformation.

A 72-year-old male presented with a 3-day history of persistent right-sided low back pain, without fever, gross hematuria, or dysuria. Contrast-enhanced abdominal computed tomography imaging revealed wall dilation and hypertrophy of the right renal pelvis-ureteral transitional segment with lipomatous enhancement, measuring approximately 3.3 × 2.7 cm.

Combined with imaging manifestations and postoperative pathological examination results, the patient was definitively diagnosed with a pyelonephric soft tissue giant cell tumor.

The patient underwent radical nephroureterectomy after systematic preoperative evaluation.

Regular postoperative follow-up was performed. Adrenal gland and pulmonary metastatic lesions were detected at 6 months postoperatively. The patient died of continuous tumor progression at 15 months after surgery.

This case illustrates that soft tissue giant cell tumor is a rare neoplasm, with renal pelvis soft tissue giant cell tumor being exceedingly uncommon. Diagnosis primarily relies on histopathological examination. Clinicians should include renal pelvis soft tissue giant cell tumor in differential diagnoses. When feasible, en bloc surgical resection is recommended. Postoperative surveillance should be intensified to facilitate early detection of recurrence, as some patients harbor potential relapse, and prognosis remains cautiously guarded.