Validation of a 10-colour flow cytometry panel compared to bone marrow biopsy to assess bone marrow infiltration in follicular lymphoma: a 5-year retrospective study

Abstract

BACKGROUND: Follicular lymphoma (FL) is the most prevalent indolent non-Hodgkin’s lymphoma. It is formed by clonal germinal centre B-cells (GCB), cells with a specific immunochemistry. When FL reaches bone marrow, patients are staged in IV Ann-Arbor stage, and this can change the therapeutical behaviour. Bone marrow involvement is mainly detected in histologic slides of bone marrow biopsy, complemented by immunohistochemistry. In most cases, these cells can be detected by flow cytometry with specific monoclonal antibodies. Flow cytometry is a quick, sensitive technique, easily performed on bone marrow aspirate cells. In the last 6-8 years it has evolved with better instruments and techniques used routinely, with very high sensitivity, and the ability to analyse up to 10-12 parametres in a single experiment. This technique can give a numerical proportion of pathologic B-cell vs normal mature B-cell or leukocytes of bone marrow, as well as it could give quantitative information of tumour load burden. OBJECTIVE: To compare the capacity of a systematized analysis of 10-colour flow cytometry (FC) panel compared to histology (Gold Standard) to detect bone marrow involvement in patients with follicular lymphoma diagnosed in the province of Girona between 2017- 2021. METHODS: The design is a transversal retrospective study. Staging tests of 138 patients with FL diagnosed in Girona between 2017-2021 will be systematically revised to analyse the validity of bone marrow aspirate flow cytometry compared to the Gold Standard, bone marrow histology. Inadequate samples will be identified and excluded from the analysis