Analytic validity refers to how well a genetic assessment measures the property or characteristic it is intended to measure. In the case of family history, analytic validity refers to the accuracy of the reported family history information. In the case of a test for a specific mutation, analytic validity refers to the accuracy of a genetic test in identifying the presence or absence of the mutation. The technical accuracy and reliability of the testing procedure and the quality of the laboratory...
Small cells that reflect neither epithelial nor stromal differentiation.
Embryonal epithelial cells resembling the liver epithelium at 6 to 8 weeks of gestation.
Well-differentiated fetal hepatocytes morphologically indistinguishable from normal fetal liver cells.
Most often the tumor consists of a mixture of epithelial hepatocyte precursors. About 20% of tumors have stromal derivatives such as osteoid, chondroid, and rhabdoid elements. Occasionally neuronal, melanocytic, squamous, and enteroendocrine elements are found. Two histologic subtypes have clinical relevance: pure fetal histology throughout the tumor and foci of small cell undifferentiated cells.
Pure fetal histology hepatoblastoma
Analysis of patients with initially resected hepatoblastoma tumors (prior to receiving chemotherapy) has suggested that those patients with pure fetal histology tumors have a better prognosis than those having an admixture of more primitive and rapidly dividing embryonal components or other undifferentiated tissues. In a study of patients with hepatoblastoma and pure fetal histology tumors, there was a 100% survival rate for patients who received four doses of single-agent doxorubicin. This suggested that patients with pure fetal histology tumors might not need chemotherapy after complete resection of a stage I tumor.[2,3] In the Children's Oncology Group (COG) study COG-P9645, 16 patients with stage I pure fetal histology hepatoblastoma with two or fewer mitoses per 10 high power fields were not treated with chemotherapy. Their retrospective PRETEXT stages were stage I (n = 4), stage II (n = 6), and stage III (n = 2). Survival was 100% with no chemotherapy given. All 16 patients entered on this study were alive with no evidence of disease at a median follow-up of 4.9 years (range, 9 months to 9.2 years). Thus, complete resection of a pure fetal hepatoblastoma may preclude the need for chemotherapy.
Small cell undifferentiated hepatoblastoma
Small cell undifferentiated hepatoblastoma is an uncommon hepatoblastoma variant that represents a few percent of all hepatoblastomas. It tends to occur at a younger age (6–10 months) compared with other cases of hepatoblastoma [5,6] and is associated with AFP normal for age at presentation.[5,7]