Grossing to reporting of Wilms tumor with emphasis on proper sampling in treatment-naive and postchemotherapy specimens and their clinicopathological correlation with outcome.

CONTEXT: Emphasis on grossing to reporting for the assessment of histopathological parameters predicting outcomes in Wilms tumor.

AIMS: To analyze various clinicopathological parameters that effect outcomes in treatment naïve and post chemotherapy Wilms tumor specimens.

SETTINGS AND DESIGN: This was a retrospective observational study.

SUBJECTS AND METHODS: All patients diagnosed with Wilms tumor between 2012 and 2018 at our institute will be included with their clinical findings, laboratory reports, and radiological findings. The patients will be categorized into two groups based on treatment protocol (Society of Pediatric Oncology (SIOP) or the National Wilms Tumor Study Group/Children's Oncology Group (COG) guidelines) used. Details of Grossing and reporting protocols used for the in pre treatment and post treatment specimens will be analyzed. Follow-up till December 2020 will be analyzed.

STATISTICAL ANALYSIS USED: Chi-square and Fisher's exact tests were used for statistical analysis.

RESULTS: A total of 36 patients with the diagnosis of Wilms tumor were included in the present study. The mean age of presentation was 3.9 ± 0.7 years, and males were more common than females. Most of them presented as abdominal mass and few with isolated hematuria. Twenty-six (72%) patients were treated under SIOP protocol with preoperative neoadjuvant chemotherapy. Ten patients underwent upfront surgery as per COG protocol. In SIOP group patients, the mean tumor size was 9.3cm. Forty percent ( n = 10) we mixed histological type followed by blastemal type constituting (32%, n = 8). Regressive and epithelial histological types constituted 16% ( n = 4) and 12% ( n = 3), respectively. In the SIOP group 72% ( n = 19) had no anaplasia and 28% ( n = 7) had anaplasia. Fifty seven percent ( n = 15) cases were Stage I, followed by 26.9% n = 7) and 11.5% ( n = 3) being Stage II and Stage III, respectively. Ten patients underwent upfront surgery as per COG protocol. The mean tumor size among this group was 8 cm ranging from 7 cm to 11 cm. Eight (80%) cases had favorable histology and two cases showed focal anaplasia. Heterologous differentiation is seen in 3 (70%). Out of the 10 cases, one case was Stage I, six were Stage 2, one was Stage III, and two were clinical Stage IV. None of the cases showed either vessel or lymph node metastasis. All the patients received adjuvant chemotherapy postsurgery and were followed up till December 2020 for (at least 3 years). Of 25 patients in the SIOP group, 18 (72%) had complete remission with no radiological evidence of residual disease. Of the 10 patients in the COG group, 6 (70%) had complete remission.

CONCLUSIONS: Histopathological evaluation of Wilms tumor is a critical aspect in the management of Wilms tumor, as tumor characteristics are different in the tumors treated under SIOP and COG protocols, which will ultimately affect the prognostic risk stratification. This necessitates the knowledge of the important grossing and reporting of these tumors under the two protocols.