Benign Renal Tumors in Pediatric Age Group: Retrospective Analysis

Benign renal tumors are extremely rare and were studied here. This series also includes a renal teratoma in a horseshoe kidney, probably only the second in the pediatric literature.

Retrospective review of children with benign renal tumors operated between 2006 and 2018 at one center.

Twelve patients (M:F ratio 10:2), age range 3 weeks (31-week gestation) to 13 years presented with large palpable renal swelling (n = 12) and hematuria (n = 3). Computed tomography (CT) scan showed features typical of the tumor. Final histopathology (age group [mean]) showed: multilocular cystic nephroma (MLCN) - n = 5 (41.7%), (11-16 months [13.6]); congenital mesoblastic nephroma (CMN) - n = 4 (33.3%) (classic 1, cellular 3) (0.75-5 months [2.125]); mature cystic teratoma - n = 1 (8.3%): (48 months, in a horseshoe kidney), and angiomyolipoma (AML) - n = 2 (16.7%) (144 months [sporadic] and 156 months [tuberous sclerosis]) One patient with cystic teratoma with no calcification on CT scan received pre-operative chemotherapy as fine-needle aspiration cytology (FNAC) reported malignant small blue cell tumor. Nephroureterectomy with Gerota's fascia could be done easily in all without intraoperative complications. Delay in presentation in MLCN and CMN led to increased symptoms and CT scan changes. All patients did well in 1.5-12 years (median 3 years) follow-up including cellular mesoblastic nephroma.

Benign renal tumors often occur in specific age groups but may overlap that of Wilms tumor. Proper interpretation of clinical presentation, CT scan, and FNAC findings help in avoiding preoperative chemotherapy. Upfront nephroureterectomy is curative. Histopathological findings decide further treatment. Children with AML and tuberous sclerosis need lifelong follow-up.