Correlation between Tyrosine Hydroxylase Immunoreactive Cells in Tumors and Urinary Catecholamine Output in Neuroblastoma Patients

PHOX2B immunolabeling: a novel tool for the diagnosis of undifferentiated neuroblastomas among childhood small round blue-cell tumors

Peripheral neuroblastic tumors are the most commonly occurring extracranial tumors in children. Although a reliable diagnosis is achievable in the majority of cases, diagnosis of a minority of peripheral neuroblastic tumor cases (especially undifferentiated neuroblastoma) poses a challenge compared with that of other pediatric small round blue-cell tumors. A panel of immunohistochemical markers and fusion transcripts is available for the diagnosis of such tumors, but the markers for neuroblastoma lack specificity and sensitivity. As the transcription factor PHOX2B is highly specific for the peripheral autonomic nervous system from which peripheral neuroblastic tumors are derived, we have assessed PHOX2B immunolabeling as a diagnostic tool in pediatric small round blue-cell tumors. We observed PHOX2B expression in all peripheral neuroblastic tumors, paragangliomas, and pheochromocytomas tested but in no other pediatric tumors among the 388 cases studied by expression microarray and the 109 cases studied by immunohistochemical analysis. We then assessed the results of PHOX2B immunohistochemistry in 12 cases of undifferentiated pediatric neoplasms: PHOX2B was expressed in 6/6 undifferentiated neuroblastomas and in no other small round blue-cell tumors. Finally, we showed that PHOX2B immunohistochemical analysis improves the diagnosis of undifferentiated neuroblastoma with high specificity and sensitivity.

Malignant rhabdoid tumor. A study with two established cell lines

BACKGROUND

Malignant rhabdoid tumor (MRT), originally described as a rare renal sarcoma in childhood, has been known to express phenotypic diversity. In this study, unique characteristics of the MRT cells were investigated by using established cell lines.

METHODS

Immunocytochemical, ultrastructural, cytogenetic, and molecular (by polymerase chain reaction, PCR) analyses were done for two MRT cell lines, one of renal and one of extrarenal origin, before and after differentiation-induction with either 12-O-tetradecanoyl phorbol-13-acetate (TPA) or transretinoic acid (RA).

RESULTS

The proliferating cells in the original tumor tissues as well as in the established cell lines demonstrated neural, epithelial, and mesenchymal markers morphologically. Both cell lines had karyotypic abnormalities including chromosome 22q11.2. The cell line from the extrarenal MRT, Tm87-16, demonstrated distinct morphologic changes with neuroblastic differentiation and produced numerous neuritic processes after treatment with either TPA or RA. The cell line from the renal MRT, STM91-01, suggested schwannian differentiation but did not change morphologically after chemical induction. Both cell lines expressed c-myc, but did not express N-myc, MyoD1, tyrosine hydroxylase, or neural cell adhesion molecule (N-CAM). With PCR and immunocytochemical study, a high level of chromogranin expression was detected by the cells of Tm87-16 only after TPA induced differentiation.

CONCLUSIONS

MRT cells demonstrated diverse phenotype of neuro-ecto-mesenchymal differentiation. The results of this study suggest that MRT may be derived from a primitive pluripotential cell, such as neural crest or equivalent. MRT, therefore, might be categorized as one of the subsets of primitive neuroectodermal tumor.