Small cell undifferentiated (SCU) histology and alpha-fetoprotein (AFP) levels below 100 ng/mL have been reported as poor prognostic factors in hepatoblastoma (HB); subsequent studies reported SMARCB1 mutations in some SCU HBs confirming the diagnosis of rhabdoid tumor. The Children’s Hepatic tumors International Collaboration (CHIC) database was queried for patients with HB who had AFP levels less than 100 ng/mL at diagnosis or were historically diagnosed as SCU HBs. Seventy-three of 1605 patients in the CHIC database were originally identified as SCU HB, HB with SCU component, or HB with low AFP levels. Upon retrospective review, they were re-classified as rhabdoid tumors (n = 11), HB with SCU component (n = 41), and HB with low AFP (n = 14). Seven were excluded for erroneously low AFP levels. Overall survival was 0% for patients with rhabdoid tumors, 76% for patients with HB with SCU component, and 64% for patients with HB with AFP less than 100 ng/mL. Patients with HB with SCU component or low AFP should be assessed for SMARCB1 mutations and, if confirmed, treated as rhabdoid tumors. When rhabdoid tumors are excluded, the presence of SCU component and low AFP at diagnosis were not associated with poor prognosis in patients diagnosed with HB.

Pediatric hepatocellular carcinoma (HCC) is a rare malignant liver tumor affecting children and adolescents and occurring either sporadically or in the context of underlying liver disease. In this review, we detail the epidemiology of pediatric HCC with a focus on predisposing factors including hepatic or systemic disease, genetic disorders, and familial cancer syndromes. We summarize existing research on the pathophysiology of pediatric HCC, including molecular mechanisms of oncogenesis, highlighting unique disease features differentiating pediatric HCC from adult HCC. We then survey the landscape of therapeutic options for pediatric HCC, including novel therapeutics. Lastly, we discuss the pathologic spectrum upon which pediatric HCC is postulated to exist, ranging from hepatoblastoma to HCC and including the hybrid entity hepatocellular neoplasm not otherwise specifed (HCN-NOS). In summary, we highlight the key clinical and molecular features of pediatric HCC that may inform future research and novel approaches to the clinical care of these patients.

Renal cancer, although still rare among individuals under 45 years of age, is on the rise in the general population. The risk and timing of subsequent renal cancer in survivors of childhood cancer is not well established. Using the SEER registry, we reported the incidence of subsequent malignant renal neoplasms after treatment for primary malignancy diagnosed under 20 years of age. We evaluated clinical characteristics, standardized incidence ratio (SIR), and Kaplan-Meier survival estimates. Fifty-three survivors developed subsequent renal cancer (54 total cases). Of these, 54.7% were female, 88.7% were white, and 13.2% were Hispanic. Mean ages at primary malignancy and subsequent renal cancer were 10.1 and 31.1 years, respectively. Forty-seven cases were second cancers, 6 were third, and 1 was fourth. For survivors of childhood cancer, the overall SIR for renal cancer was 4.52 (95% CI: 3.39-5.89). The 5-year overall survival rate after development of subsequent renal cancer was 73% (95% CI: 58%-83%). Renal cancer occurs 4.5 times more frequently in childhood cancer survivors than in the general population, necessitating long-term care considerations.