Abstract: FR-PO1282
A Diagnostic Impostor: Adrenal Hemorrhagic Mass Mimicking Postbiopsy Hematoma
Session Information
- Onconephrology: Diagnostic Dilemmas, Therapy-Related Toxicities, and Clinical Cases
October 23, 2026 | Location: Exhibit Hall A, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Onconephrology
- 1600 Onconephrology
Authors
- Pradhan, Ajay B., Oregon Health & Science University, Portland, Oregon, United States
- Selvam, Sri Abirami, Oregon Health & Science University, Portland, Oregon, United States
- Mistry, Nupur, Oregon Health & Science University, Portland, Oregon, United States
Introduction
Acute interstitial nephritis (AIN) is a reversible cause of acute kidney injury (AKI) often linked to medications, including ifosfamide. Diagnosis frequently requires kidney biopsy, which carries risks such as perinephric hematoma. We describe a presumed post-biopsy hematoma later identified as a metastatic disease.
Case Description
A 29-year-old male with recurrent synovial sarcoma previously treated with chemotherapy and radiation developed AKI after re-treatment with ifosfamide. Kidney biopsy showed AIN attributed to ifosfamide and over-the-counter supplements. Despite discontinuing supplements, creatinine continued to rise. Two months later, he presented with left flank pain and a 9-cm hyperdense retroperitoneal mass on imaging. A hemoglobin drop from 9 g/dL to 5 g/dL led to presumptive diagnosis of post-biopsy hematoma. Serial imaging over three weeks showed persistent size and appearance, and creatinine remained elevated at 3.2–3.6 mg/dL. Five months after biopsy, surveillance imaging reviewed by another radiologist recharacterized the lesion as a left adrenal mass concerning for metastasis. Surgical excision confirmed metastatic synovial sarcoma, after which creatinine improved to 2.7 mg/dL, suggesting compressive renal dysfunction. A retrospective review identified an adrenal mass associated with hemorrhage that had been misclassified initially.
Discussion
Post-biopsy hematomas usually appear within days of biopsy and gradually decrease in size and attenuation. In this case, interval enlargement was inconsistent with expected hematoma evolution, highlighting diagnostic anchoring bias. In patients with malignancy, retroperitoneal masses should prompt consideration of metastatic disease, as hemorrhagic adrenal metastases can closely mimic post-biopsy hematoma on imaging.
Acknowledgment
We would like to acknowledge Dr. Bryan Foster for their valuable assistance in reviewing the radiographic studies and retrieving the imaging used in this case report presentation. Their expertise and support were instrumental in accurately characterizing the imaging findings and enhancing the quality of this presentation.