Bone marrow evaluation in pediatric patients

The reliability of bone marrow cytology as response criterion in metastatic neuroblastoma

BACKGROUND

The quantitative assessment of neuroblastoma cell content in bone marrow aspirates for response evaluation has been introduced recently. Data on the concordance of interobserver reports are lacking so far.

METHODS

Investigators of seven European countries representing national reference or large oncological centers convened in 2016. They agreed to quantitatively assess routine bone marrow smears of the participating institutions and to discuss the discrepant results in joint meetings.

RESULTS

From 2017 through 2019, three cytology rounds with 24, 28, and 28 bone marrow samples were run evaluating the representativity of the smears (yes/[restricted]/no) and the presence of tumor cells (yes/no and %). The comparison of the reports using κ (Fleiss) and α (Krippendorff) statistics demonstrated no robust reliabilities. The agreement on the representativity was moderate to poor, on the presence of tumor cells moderate to good, and on the percentage of tumor cells slight to moderate. Though the value of cytology is unquestioned to detect even tiny metastatic cells in bone marrow, the investigators unanimously agreed that a reliable quantification of the tumor cell content in bone marrow smears is unrealistic. For the key issue of representativity, a new practical definition was developed.

CONCLUSION

For any work with bone marrow aspirates, the representativity of the material is of paramount importance. A practical definition is proposed. A reliable quantitative cytological assessment of tumor cell content in bone marrow aspirates is not feasible in metastatic neuroblastoma. Therefore, its use as response criterion should be reconsidered.

CongenitalMLL-positive B-cell acute lymphoblastic leukemia (B-ALL) switched lineage at relapse to acute myelocytic leukemia (AML) with persistent t(4;11) and t(1;6) translocations and JH gene rearrangement

Congenital acute leukemia is a rare form of childhood leukemia, in which lineage conversion at relapse is very rarely reported. Here we describe a case of congenital B-cell acute lymphoblastic leukemia (B-ALL) with t(4;11) and t(1;6) translocations, which at relapse underwent a switch to monocytic lineage with persistence of the original cytogenetic translocations and clonal rearrangement of the JH gene. Similar to the other described cases of congenital acute leukemia with lineage conversion, our case had a MLL gene rearrangement and followed an aggressive clinical course.

Recommended curriculum for teaching hematopathology to subspecialty hematopathology fellows

The performance and interpretation of clinical hematology and hematopathology laboratory tests and diagnosis of benign or malignant hematolymphoid disorders present unique challenges to hematopathology fellow trainees. To assist hematopathology fellowship program directors in preparing trainees to meet these challenges, a task force of pathologists with expertise in hematopathology developed a suggested training curriculum that includes a comprehensive list of topics in the areas of analytic hematology, bone marrow pathology, lymph node pathology, splenic pathology, lymphoma diagnostics, cytogenetics, and molecular diagnostics. This report also includes recommendations for training experiences that will facilitate the transition of subspecialty residents to practicing consultants in hematopathology.