Abstract: TH-PO1150
Not Just an Infection: Upper Tract Urothelial Carcinoma Presenting as Psoas Abscess
Session Information
- Onconephrology: Emerging Biomarkers, Preclinical Models, Clinical Challenges, and Therapeutic Strategies
October 22, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1600 Onconephrology
Authors
- Naseem, Rabia, Dartmouth Hitchcock Medical Center, Lebanon, New Hampshire, United States
- Agarwal, Joshika, Mercy Fitzgerald Hospital, Darby, Pennsylvania, United States
- Batool, Humera, Mercy Fitzgerald Hospital, Darby, Pennsylvania, United States
Introduction
Upper tract urothelial cancer (UTUC) accounts for 5–10 % of all urothelial cancers and is uncommon with increasing incidence over the past 30 years. Overall, two-thirds of UTUCs are invasive at diagnosis compared with 15–25% of bladder tumors. Most common symptoms include hematuria (70%-80%), flank pain secondary to clot, hydronephrosis secondary to obstruction due to tumor burden or local growth is less common occurring in approximately 20-32% of cases. Studies have suggested the presence of hydronephrosis is a prognostic indicator for advanced disease.
Case Description
A 75-year-old male with hypertension presented with four-week right lower quadrant pain. Outpatient imaging demonstrated ruptured appendicitis with psoas abscess. Managed with drainage catheter and broad-spectrum antibiotics. One day post-discharge, he represented with exertional dyspnea and right lower extremity discoloration. Vitals showed hypertension, tachycardia, & tachypnea requiring supplemental oxygen. Labs: creatinine 1.9, sodium 129, lactate 3.9, WBC 19.6, D-dimer >20.00. CT chest revealed pulmonary emboli. CT abdomen showed right hydronephrosis & hydroureter proximal to psoas abscess. CT angiography demonstrated a multilobulated necrotic retroperitoneal mass with occlusive IVC thrombus extending throughout the right lower extremity vasculature. He underwent iliofemoral thrombectomy, venoplasty, & IVC filter placement, then transitioned to oral anticoagulation. Retroperitoneal biopsy revealed malignant cells positive for AE1/AE3, CK7, and GATA3, consistent with urothelial or breast primary. Retrograde pyelogram confirmed significant mid/distal ureteral narrowing, establishing the diagnosis of right ureteral urothelial carcinoma.
Discussion
Urothelial carcinoma originates from urothelial cells lining the urinary tract, comprising 90-95% bladder cancer & 5-10% UTUC. Typical presentation includes hematuria, flank pain, and hydronephrosis. Our case uniquely presented as ruptured appedicitis with retroperitoneal psoas abscess complicated by AKI, hyponatremia, occlusive VTE, & sepsis. Psoas abscess results from hematogenous seeding, trauma, or direct spread from adjacent structures. Initial presentation as psoas abscess has not been reported with UTUC. Carcinoma should remain on the differential in elderly patients presenting with psoas abscess, hydronephrosis, hyponatremia due to SIADH particularly with elevated creatinine or ureteral involvement.