Presence of differentiating neuroblasts in bone marrow is a favorable prognostic factor for bone marrow metastatic neuroblastoma at diagnosis

MYCN amplification predicts poor prognosis based on interphase fluorescence in situ hybridization analysis of bone marrow cells in bone marrow metastases of neuroblastoma

BACKGROUND

MYCN gene amplification is related to risk stratification. Therefore it is important to identify accurately the level of the MYCN gene as early as possible in neuroblastoma (NB); however, for patients with bone marrow (BM) metastasis who need chemotherapy before surgery, timely detection of the MYCN gene is not possible due to the unavailability of primary tumors.

METHODS

MYCN gene status was evaluated in 81 BM metastases of NB by interphase fluorescence in situ hybridization (FISH) analysis of BM cells. The clinicobiological characteristics and prognostic impact of MYCN amplification in NB metastatic to BM were analyzed.

RESULTS

MYCN amplification was found in 16% of patients with metastases, and the results were consistent with the primary tumors detected by pathological tissue FISH. MYCN amplification was associated with age, lactate dehydrogenase (LDH) levels and prognosis (P = 0.038, P < 0.001, P = 0.026). Clinical outcome was poorer in patients with MYCN amplification than in those without amplification (3-year EFS 28.8 ± 13.1 vs. 69.7 ± 5.7%, P = 0.005; 3-year OS 41.5 ± 14.7 vs. 76.7 ± 5.5%, P = 0.005).

CONCLUSIONS

MYCN amplification predicts a poor outcome in NB metastatic to BM, and interphase FISH of bone marrow cells provides a timely direct and valid method to evaluate the MYCN gene status.

Morphologic alteration of metastatic neuroblastic tumor in bone marrow after chemotherapy

Background

The aim of this study is to evaluate the histologic features of metastatic neuroblastic tumors (NTs) in bone marrow (BM) before and after chemotherapy in comparison with those of primary NTs.

Methods

A total of 294 biopsies from 48 children diagnosed with NTs with BM metastasis were examined. There were 48 primary neoplasm biopsies, 48 BM biopsies before chemotherapy, 36 primary neoplasm excisional biopsies after chemotherapy, and 162 BM biopsies after chemotherapy.

Results

Metastatic NTs in BM before chemotherapy were composed of undifferentiated and/or differentiating neuroblasts, but had neither ganglion cells nor Schwannian stroma. Metastatic foci of BM after chemotherapy were found to have differentiated into ganglion cells or Schwannian stroma, which became more prominent after further cycles of chemotherapy. Persistence of NTs or tumor cell types in BM after treatment did not show statistically significant correlation to patients' outcome. However, three out of five patients who newly developed poorly differentiated neuroblasts in BM after treatment expired due to disease progression.

Conclusions

Metastatic NTs in BM initially consist of undifferentiated or differentiating neuroblasts regardless of the primary tumor subtype, and become differentiated after chemotherapy. Newly appearing poorly differentiated neuroblasts after treatment might be an indicator for poor prognosis.