全髖關節置換術後骨盆假性腫瘤合併尿滯留之罕見表現

林冠廷¹、林克勳^1,2

¹臺北市立萬芳醫院泌尿科－委託臺北醫學大學辦理；²臺北醫學大學泌尿學科

Pelvic Pseudotumor Presenting as Urinary Retention 17 Years After Total Hip Arthroplasty: A Case Report

Kuan-Ting Lin¹, Ke-Hsun Lin^1,2

Department of Urology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan¹; Department of Urology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan²

Introduction

Complications associated with metal-on-metal (MOM) prostheses, such as adverse reactions to metal debris (ARMDs), include pseudotumor (PT) formation, metallosis, and soft tissue necrosis. We present a case of urinary retention caused by a pelvic pseudotumor related to an adverse local tissue reaction following hip arthroplasty.

Presentation of Case

This 70-year-old male had a history of total hip replacement 17 years prior. He initially presented to the emergency department with difficulty urinating. A Foley catheter was inserted, and he was referred to the urology department for further evaluation. Digital rectal examination revealed a left-sided elastic protruding lesion. Transrectal ultrasound of the prostate demonstrated prostate enlargement with heterogeneous echotexture, with an estimated prostate volume of 128 g. Review of his medical records showed that his prostate volume had been 28 g two years ago. Due to the rapid increase in prostate size, contrast-enhanced abdominal and pelvic computed tomography was performed. Imaging revealed a cystic lesion with wall thickening extending from the left hip to the pelvic sidewall, raising suspicion for a synovial cyst or abscess. The lesion compressed the urinary bladder and prostatic urethra. Transperineal aspiration of the cystic lesion was performed. A total of 100 mL of bloody fluid was aspirated and sent for cytology, culture, and synovial analysis. Post-aspiration digital rectal examination revealed no palpable lesion, and urinary retention resolved after Foley catheter removal. An orthopedic surgeon was consulted and favored a diagnosis of pseudotumor related to prior hip arthroplasty.

Serum cobalt was mildly elevated at 1.7 μg/L. Synovial analysis and cytology of the aspirated fluid were consistent with a hematoma. The patient reported left hip pain for one year, which had been managed conservatively at another hospital. Revision hip arthroplasty was recommended after discussion with the orthopedic team.

Discussion and Conclusion

Pseudotumor formation is an uncommon but increasingly recognized complication following total hip arthroplasty (THA), representing a manifestation of adverse local tissue reaction (ALTR). Although it typically presents with local hip symptoms, extrapelvic extension causing compression of pelvic organs is rare.

In this case, a large cystic pelvic pseudotumor developed 17 years after THA, resulting in urinary retention due to compression of the bladder and prostatic urethra. Imaging demonstrated a cystic lesion extending from the hip joint into the pelvis, and aspiration yielded bloody fluid consistent with chronic inflammatory synovial processes. Immediate symptom relief after aspiration supported a compressive etiology. Mildly elevated serum cobalt levels further suggested ALTR, although such elevations may be subtle in long-standing cases. Given the risk of progression and recurrence, revision arthroplasty remains the definitive treatment. Clinicians should consider pelvic pseudotumor in patients with prior THA who present with unexplained urinary obstruction.