CYTOGENETIC AND IMMUNOHISTOCHEMICAL ANALYSIS OF AN ADULT ANAPLASTIC NEUROBLASTOMA

Neuroblastomas in children are common tumors and are characterized by a number of recurrent cytogenetic and molecular changes. Adult neurobl astomas are rare, and their relationship to pediatric neuroblastomas i s not clear. We report an anaplastic neuroblastoma presenting in a 28- year-old man. Histopathologic identification of the tumor as a neurobl astoma was problematic, and the initial diagnosis was poorly different iated sarcoma. Tumor cells expressed immunoreactivity for tyrosine hyd roxylase in addition to generic neuroendocrine markers, consistent wit h catecholamine-synthesizing ability. They also extended long, branchi ng neurites in vitro. The tumor was positive for immunoreactive trkA. The karyotype after 6 days in culture was found to be 42,XY with multi ple chromosomal abnormalities. The only abnormality shared with pediat ric neuroblastomas was a rearrangement of chromosome 17q. Double minut e chromosomes or homogeneously staining regions associated with N-myc amplification were not present. To our knowledge, this is the first re ported karyotype of an adult neuroblastoma. The cytogenetic findings, together with expression of trkA, suggest that the tumor was more clos ely related to the favorable prognosis neuroblastomas of infancy than to the poor prognosis tumors that occur in older children, despite its unfavorable histology.