A case of composite neuroblastoma composed of histologically and biologically distinct clones.

We report a case of a 12-month-old girl with stage 3 neuroblastoma composed of 2 distinct clones in the adrenal primary tumor. One clone showed neuroblastoma, poorly differentiated subtype with a low mitosis-karyorrhexis index (favorable histology), and the other was neuroblastoma, poorly differentiated subtype with a high mitosis-karyorrhexis index (unfavorable histology), according to the International Neuroblastoma Pathology Classification. Fluorescent-labeled in-situ hybridization using the formalin-fixed, paraffin-embedded material showed that the MYCN oncogene was amplified in the latter clone but not in the former clone. Lymph nodes from ipsilateral and contralateral sides contained metastatic neuroblastoma of the latter clone. It is well documented that tumors in the Ganglioneuroblastoma, nodular (composite, Schwannian stroma-rich/stroma-dominant and stroma-poor) category are composite and composed of multiple clones. To our knowledge, however, this is the 1st case report of composite tumor with biologically favorable and unfavorable clones in the Neuroblastoma (Schwannian stroma-poor) category.