Improving Detection of Metastatic Neuroblastoma in Bone Marrow Core Biopsies: A Proposed Immunohistochemical Approach

Flow cytometry of bone marrow aspirates from neuroblastoma patients is a highly sensitive technique for quantification of low-level neuroblastoma

Background: Bone marrow involvement is an important aspect of determining staging of disease and treatment for childhood neuroblastoma. Current standard of care relies on microscopic examination of bone marrow trephine biopsies and aspirates respectively, to define involvement. Flow cytometric analysis of disaggregated tumour cells, when using a panel of neuroblastoma specific markers, allows for potentially less subjective determination of the presence of tumour cells.

Methods: A retrospective review of sequential bone marrow trephine biopsies and aspirates, performed at Great Ormond Street Hospital, London, between the years 2015 and 2018, was performed to assess whether the addition of flow cytometric analysis to these standard of care methods provided concordant or additional information.

Results: There was good concurrence between all three methods for negative results 216/302 (72%). Positive results had a concordance of 52/86 (61%), comparing samples positive by flow cytometry and positive by either or both cytology and histology.  Of the remaining samples, 20/86 (23%) were positive by either or both cytology and histology, but negative by flow cytometry. Whereas 14/86 (16%) of samples were positive only by flow cytometry.

Conclusions: Our review highlights the ongoing importance of expert cytological and histological assessment of bone marrow results. Flow cytometry is an objective, quantitative method to assess the level of bone marrow disease in aspirates.  In this study, flow cytometry identified low-level residual disease that was not detected by cytology or histology. The clinical significance of this low-level disease warrants further investigation.

New Prognostic Indicators in Pediatric Adrenal Tumors: Neuroblastoma and Adrenal Cortical Tumors, Can We Predict When These Will Behave Badly?

Pediatric adrenal tumors are unique entities with specific diagnostic, prognostic, and therapeutic challenges. The adrenal medulla gives rise to peripheral neuroblastic tumors (pNTs), pathologically defined by their architecture, stromal content, degree of differentiation, and mitotic-karyorrhectic index. Successful risk stratification of pNTs uses patient age, stage, tumor histology, and molecular/genetic aberrations. The adrenal cortex gives rise to adrenocortical tumors (ACTs), which present diagnostic and prognostic challenges. Histologic features that signify poor prognosis in adults can be meaningless in children, who have superior outcomes. The key clinical, pathologic, and molecular findings of pediatric ACTs have yet to be completely identified.

Combined use of multiparametric flow cytometry and cytomorphology to enhance detection of neuroblastoma metastatic cells in bone marrow

INTRODUCTION

In the context of neuroblastoma (NB), the screening for bone marrow (BM) metastasis is a recurrent issue for hematology laboratory routine practice. Detection of low tumor burden using light microscopy is often difficult. In this regard, our objective was to evaluate the performance of multiparametric flow cytometry (FC) for detecting NB metastatic cells in BM.

METHODS

We applied a new FC multiparametric panel allowing the analysis of the co-expression of 5 surface markers: GD2 (disialoganglioside 2), CD9, CD56, CD81, and CD90, on CD45-negative BM cell populations, and compared results with BM biopsy immunohistochemistry, which is the reference method.

RESULTS

In spike-in tests, the multiparametric FC successfully detected NB cells mixed in peripheral blood mononuclear cells to a level of 0.01%. FC analysis was performed on 45 sets of BM aspirates sampled from 21 children, either at diagnosis or during follow-up. Combining multiparametric FC with light microscopy improved NB metastasis detection, with a higher sensitivity (76.9% vs 61.5%) and a higher specificity (94.4% vs 77.8%) as compared to light microscopy alone. At the time of diagnosis, multiparametric FC detected NB metastatic cells in all cases.

CONCLUSION

These results illustrate the performance of multiparametric FC analysis to detect metastatic BM infiltration of NB. This is of particular interest in an emergency context, since when combined with light microscopy, it enhances the detection of metastatic invasion within a short timeframe, allowing an adapted and rapid clinical management.

Recommendations for the standardization of bone marrow disease assessment and reporting in children with neuroblastoma on behalf of the International Neuroblastoma Response Criteria Bone Marrow Working Group

BACKGROUND

The current study was conducted to expedite international standardized reporting of bone marrow disease in children with neuroblastoma and to improve equivalence of care.

METHODS

A multidisciplinary International Neuroblastoma Response Criteria Bone Marrow Working Group was convened by the US National Cancer Institute in January 2012 with representation from Europe, North America, and Australia. Practical transferable recommendations to standardize the reporting of bone marrow disease were developed.

RESULTS

To the authors' knowledge, the current study is the first to comprehensively present consensus criteria for the collection, analysis, and reporting of the percentage area of bone marrow parenchyma occupied by tumor cells in trephine-biopsies. The quantitative analysis of neuroblastoma content in bone marrow aspirates by immunocytology and reverse transcriptase-quantitative polymerase chain reaction are revised. The inclusion of paired-like homeobox 2b (PHOX2B) for immunohistochemistry and reverse transcriptase-quantitative polymerase chain reaction is recommended. Recommendations for recording bone marrow response are provided. The authors endorse the quantitative assessment of neuroblastoma cell content in bilateral core needle biopsies-trephines and aspirates in all children with neuroblastoma, with the exception of infants, in whom the evaluation of aspirates alone is advised. It is interesting to note that 5% disease is accepted as an internationally achievable level for disease assessment.

CONCLUSIONS

The quantitative assessment of neuroblastoma cells is recommended to provide data from which evidence-based numerical criteria for the reporting of bone marrow response can be realized. This is particularly important in the minimal disease setting and when neuroblastoma detection in bone marrow is intermittent, where clinical impact has yet to be validated. The wide adoption of these harmonized criteria will enhance the ability to compare outcomes from different trials and facilitate collaborative trial design. Cancer 2017;123:1095-1105. © 2016 American Cancer Society.

An Evidence-based Recommendation for a Standardized Approach to Detecting Metastatic Neuroblastoma in Staging Bone Marrow Biopsies

Neuroblastoma is a common malignant tumor of childhood. Accurate bone marrow (BM) evaluation for metastatic tumor is essential; however, no standardized pathologic workup exists for staging BMs. We examined the diagnostic yield of various BM components and optimal core biopsy (CB) length as part of developing evidence-based recommendations for BM evaluation. After obtaining institutional review board approval, 160 BM biopsies from 50 neuroblastoma patients were retrospectively selected. Hematoxylin and eosin-stained CB and Wright-stained aspirates were scored as positive, negative, or indeterminate. Total/trabecular CB lengths were measured using cellSens software and a DP71 camera (Olympus). Of the 160 BMs, 72 were positive for tumor in any component. Of these, 33 (45.8%) were positive in a single portion of the specimen: 19 CBs and 14 aspirates. Compared with overall diagnosis, sensitivities were as follows: CB 76.3%; aspirate 67.1%; core/aspirate combined 94.7%. Diagnostic CBs had significantly longer trabecular length than nondiagnostic CBs (6.74 mm vs 4.03 mm, P = .006). Positive CBs had longer trabecular space than negative marrows (7.91 mm vs 6.25 mm, P = .002). Nearly 50% of our positive specimens showed diagnostic discordance among the various components examined. However, combining CB and aspirate examination improved sensitivity for tumor detection. We therefore recommend bilateral CBs (>1 cm each) and aspirates for the optimal evaluation of BM for metastatic neuroblastoma.