Primary intrarenal/perirenal neuroblastoma mimicking wilms tumor at presentation in a 5-year-old girl: a case report from siriraj hospital

Neuroblastomas that primarily arise in the intrarenal/perirenal region are uncommon and can mimic pediatric renal tumors at their presentation. Due to difference in clinical management and prognosis, distinguishing neuroblastoma that primarily occurs in the intrarenal/perirenal area from pediatric renal tumors is crucial. Recognition of their characteristic features is important to avoid misdiagnosis and inappropriate treatment. Less than 100 cases have been described. The authors, therefore, report a 5-year-old girl with primary intrarenal/perirenal neuroblastoma that was preoperatively misdiagnosed as Wilms tumor. The patient presented with a right-sided abdominal mass without other remarkable clinical and laboratory findings. CT whole abdomen showed a large retroperitoneal mass likely originating from intrarenal and/or perirenal region of the right kidney. No evidence of metastatic disease was detected by CT chest, Tc-99m whole body bone scan, bone marrow aspiration and biopsy. The resection specimen revealed a large, well-circumscribed mass that replaced the middle part and lower pole of the right kidney and involved the renal hilum and perirenal soft tissue. The histologic findings confirmed the diagnosis of poorly differentiated neuroblastoma. To our knowledge, the current case is the first case of primary intrarenal/perirenal neuroblastoma that has been reported in Thailand. The tumor histopathology is very crucial to establish the definite diagnosis and planning of treatment.