Large cell neuroblastoma – Phenotypical variant of MYC-driven neuroblastoma: Report of 2 cases with different molecular characteristics

Two rare cases of large cell neuroblastoma (LCN) are reported. Case 1 (8-year-old male) showed the appearance of Neuroblastoma, poorly differentiated subtype with a high MKI (Mitosis-Karyorrhexis Index) and Case 2 (7-year-old male) was Neuroblastoma, undifferentiated subtype with a low MKI. Both cases were classified into the Unfavorable Histology Group according to the International Neuroblastoma Pathology Classification and their tumors were characteristically composed of neuroblastic cells with enlarged and often pale or vacuolated nuclei containing one or few prominent nucleoli. While LCN is a phenotypical variant of MYC-driven neuroblastoma overexpressing MYC-family protein, the two tumors presented in this report had different molecular characteristics: One had n-MYC oncogene amplification with n-MYC protein overexpression (Case 1), and the other had c-MYC protein overexpression without genomic amplification (Case 2). It was also noted that the tumor cells in Case 2 demonstrated “aberrant” desmin expression by immunostaining.