INTRODUCTION
Peripheral neuroblastic tumors (pNTs), which comprise neuroblastoma (NB), ganglioneuroblastoma, and ganglioneuroma, have well-established prognostic factors such as age at diagnosis, clinical stage (International Neuroblastoma Staging System), MYCN status, chromosomal abnormalities (Chromosome 1p and 11q deletions), DNA ploidy pattern, and histopathology classification (International Neuroblastoma Pathology Classification; INPC). Based on these factors, NB cases can be classified into four categories: very low-risk, low-risk, intermediate-risk, or high-risk; which will in turn determine the treatment protocol applied.1-5MYCN -amplification (MYCN -A) demonstrate is a common histologic characteristic of NB, whereas undifferentiated/poorly differentiated NB subtype harbor a high mitosis-karyorrhexis index (MKI), which is considered unfavorable histology (UH) in INPC classification.
According to INPC, the MYCN -A is rarely found in a tumor showing favorable histology (FH: pathologically good prognosis group). Tumors within the MYCN -A and FH group account for only 1.1% of all NB cases, and their treatment remains controversial. Suganuma et al. reported a case of MYCN -A+FH genotype–phenotype discordant and analyzed its histopathological nature. Their analysis revealed that such discordant cases could be divided into good or poor prognosis groups based on the nuclear morphology and the presence of N-myc expression, resulting in subclassification of ”conventional” (“salt and pepper” nucleoli) and ”Bull’s eye” (prominent nucleoli) tumors.
Herein, we present two genotype–phenotype discordant NB cases, which further support the relevance of histopathology, along with N-myc expression analysis, as important factors for selecting an appropriate treatment for pNTs.