A case series and literature review of renal anastomosing hemangioma: An often-misdiagnosed benign tumor.

Background: Renal anastomosing hemangiomas (RAHs) are rare. This study aimed to summarize the clinical, pathological, and imaging characteristics of RAH. Materials and methods: We retrospectively analyzed 14 patients who underwent surgery for RAH at our center between December 2014 and December 2023. In addition, we conducted a literature review of case reports and case series on RAH published between 2009 and 2023. Results: Renal anastomosing hemangioma predominantly affected men and was typically solitary. More than half of the tumors were localized in the renal parenchyma. Approximately 70.7% (65/92) of patients were asymptomatic. The mean maximum tumor diameter was 20 mm (range, 14-28 mm). A total of 35.2% (37/105) of patients had end-stage renal disease. Patients with end-stage renal disease and RAH are generally younger and have bilateral multifocal tumors. However, these tumors were smaller in size. Continent of origin of patient and tumor location were significant factors influencing tumor size. No tumor recurrence or distant metastases were observed during a median follow-up period of 18 months. Postoperative pathological staining remains the criterion standard for diagnosing RAH; however, preoperative multiparametric magnetic resonance imaging provides valuable diagnostic information. The RAH typically exhibits peripheral, discontinuous, and nodular enhancement during the corticomedullary phase, followed by centripetal fill-in enhancement during the excretory phase. Preoperative ultrasound-guided percutaneous biopsy is recommended when these characteristic magnetic resonance imaging features are observed. Conclusions: Renal anastomosing hemangioma is a rare benign renal tumor that is often misdiagnosed on imaging, leading to potential overtreatment. Surgeons must be well versed in the differential diagnosis of tumors to provide optimal treatment for patients.