Atypical CT findings of renal neuroblastoma: a case report.

Background: The neuroblastoma (NB) is a highly malignant tumor of the ectoderm of sympathetic nerve cells and one of the most common malignant tumors in children, which can occur in any part of the sympathetic nerve plexus distribution, however it is less common in the kidney.

Case Description: Here we present a case of a 4-year-old boy who came to our hospital for medical help because of "abdominal distension for 1 day". Abdominal computed tomography (CT) revealed a huge retroperitoneal soft tissue mass with unclear boundaries with kidneys and adrenal glands, and low-density cystic necrosis areas were seen in the tumor. Contrast-enhanced scan showed that the mass showed mild heterogeneous enhancement. Based on these findings in the patient, he was initially considered to have Wilms tumor, but was finally pathologically confirmed as renal NB. The purpose of this article is to provide the clinicopathological features and CT manifestations of renal NB, and to discuss its differential diagnosis with other renal tumors, in order to better provide clinicians with a better understanding of the rare solid tumor. The renal NB is usually a large lobulated soft tissue mass with unclear boundary and incomplete capsule, which is prone to hemorrhage, necrosis, cystic degeneration and calcification. On CT, the mass is usually isodensity or slightly hypodense, and the cystic degeneration and necrosis area is hypodense, and on contrast-enhanced scan, it can be mildly to significantly enhanced, but the cystic degeneration and necrosis area have no enhancement.

Conclusions: The CT findings of our case were atypical and overlapped with those of Wilms, so our case suggests that renal NB should be considered as one of the differential diagnoses of Wilms, the most common malignancy of the kidney in children.