Metanephric Adenoma: A Case Report of a Rare Benign Renal Tumor

Introduction: Metanephric adenomas (MAs) of the kidney are rare benign epithelial lesions in the kidney that have been described in the literature, mainly through case reports, representing ~0.2% of renal masses. No prior case reports have been published from Nepal. We report one such case with MA presented to our center. Case presentation: A 25-year-old lady presented with complaints of recurrent hematuria for the past 6 months. Ultrasound of the abdomen revealed left gross hydronephrosis and reduced left renal parenchyma. A contrast-enhanced computerized scan of the abdomen and pelvis showed a heterogeneously enhancing soft tissue density lesion 65 mm×57 mm at the left renal pelvis extending into mid calyx and distally to proximal ureter, ~34 mm distal to pelviureteric junction causing moderate hydronephrosis, likely urothelial cell carcinoma. Urine cytology was negative for malignancy. Laparoscopic left nephroureterectomy with bladder cuff excision lymphadenectomy was done. The histopathology report came out to be consistent with MA and the lymph nodes were negative for malignancy. Immunohistochemistry study showed that the cells were positive for PAX8. During follow-up, she did not have hematuria and her postoperative period was uneventful. Discussion: From this report, we want to highlight the need to consider MA as a differential diagnosis of renal mass and differentiate MA from upper tract urothelial carcinoma, renal cell carcinoma, Wilms tumor, and papillary adenomas. Conclusion: MA is a rare renal lesion that may present as upper tract urothelial carcinoma. MA should be evaluated through histology and immunohistochemistry studies.

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“…Based on the results of pathologic features and IHC (positive vimentin, WT1, and PAX8), the diagnosis of MA can be established [12] .…”

Section: Discussionmentioning

confidence: 99%