ROLE OF THE PREOPERATIVE RETROPERITONEAL CORE NEEDLE BIOPSY (CNB) IN THE DIFFERENTIAL DIAGNOSIS OF SUSPECTED MALIGNANT RENAL TUMORS IN CHILDREN.

Background: Childhood cancers represent a significant health concern worldwide, with malignant renal tumors accounting for approximately 7% of all childhood cancers. Differentiation of Wilms tumor (WT) from non-Wilms renal tumors (NWRT) is essential as the management of these two groups of         tumors are very different, especially if we believe in the SIOP protocol of administering neo-adjuvant chemotherapy (NACT) in patients with WT. Aims- This study     done to evaluate role of the preoperative retroperitoneal core needle biopsy (CNB) in the differential diagnosis of suspected malignant renal tumors in children. Material and methods: this is a prospective study done in NSCB medical college Jabalpur from January 2023 to January 2024. CNB was done in 20 patients (23 renal biopsies as 3 patients had bilateral tumors) with suspected malignant renal tumors. Those diagnosed as WT on CNB received NACT followed by nephrectomy and adjuvant therapy. Results: Out of the 23 renal biopsies, 21 were diagnosed as WT while the other 2  as malignant rhabdoid tumors of kidney (MRTK). One patient developed abdominal distension and respiratory distress after CNB. On HPE of the excised surgical specimen of those who received NACT for WT (diagnosed on CNB), 19 samples were confirmed as WT, while 2 were diagnosed as clear cell sarcoma of the kidney (CCSK). Of the 2 tumors that were diagnosed as MRTK on CNB, 1 was confirmed as MRTK and the other was diagnosed as CCSK on HPE of the excised specimen. The concordance between the HPE of CNB and the excised surgical specimen was 91%. Conclusion: Pre-therapy CNB is a sensitive tool to differentiate WT from NWRT. The sensitivity, specificity, positive predictive value and negative predictive value of CNB in the diagnosis of renal tumors are 89%, 50%, 89% and 100% respectively.