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A 32-year-old woman presented to the Department of Orthopedic Surgery with right gluteal pain. Routine laboratory investigations were unremarkable, with preserved renal function (eGFR, 100.0 mL/min/1.73 m2). However, lumbar magnetic resonance imaging revealed multiple large bilateral paraspinal masses (panels A–C), raising concerns for retroperitoneal tumors. She was subsequently referred to our hospital for further evaluation. Computed tomography demonstrated that these lesions represented marked renal pelvic dilatation (panels D and E). A review of her medical history revealed a previous diagnosis of arginine vasopressin resistance (AVR) attributed to compound heterozygous pathogenic variants in the aquaporin-2 (AQP2) gene. She reported a daily urine output of approximately 8 L with an equivalent fluid intake. Recognition of this condition prevented unnecessary invasive procedures, and because the gluteal pain improved with rest, it was considered unrelated to hydronephrosis. Owing to sustained high fluid intake and polyuria, patients with AVR or arginine vasopressin deficiency may develop hydronephrosis [1], which can be mistaken for mass-like lesions [2]. Accurate diagnosis of hydronephrosis is essential to distinguish it from neoplastic processes and to initiate treatment that prevents renal failure or urinary tract infections. This case highlights the importance of revisiting previous diagnoses when confronted with perplexing radiologic findings.
Contributor Information
Yuma Motomura, Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan.
Hironori Bando, Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan.
Contributors
All authors made individual contributions to the authorship. Y.M. was involved in the management of the patient and in manuscript preparation and submission. H.B. was involved in the diagnosis and management of the patient and reviewed the manuscript. All authors reviewed and approved the final draft.
Funding
No public or commercial funding.
Disclosures
None declared.
Informed patient consent for publication
Signed informed consent was obtained directly from the patient.
References
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