Improvement of diagnosis in children with Burkitt lymphoma in Kenya: feasibility study for the implementation of fluorescence in situ hybridisation testing for MYC and the MYC/IGH translocation

Abstract

Background: Indiana University (IU) initiated fluorescence in situ hybridisation (FISH) methodology for Burkitt Lymphoma (BL) to advance the accuracy and speed of diagnosis in the AMPATH Reference Laboratory at Moi Teaching and Referral Hospital (MTRH) in Eldoret, Kenya. Standard diagnostic testing for BL at MTRH includes morphology of the biopsy specimen or aspirate and limited immunohistochemistry panels.

Methods: Tumour specimens from 19 children enrolled from 2016 to 2018 in a prospective study to improve the diagnosis and staging of children with suspected BL were evaluated. Touch preps from biopsy specimens or smears from fine needle aspiration were collected, stained with Giemsa and/or H&E and reviewed by pathologists to render a provisional diagnosis. Unstained slides were stored and later processed for FISH. Duplicate slides were split between two laboratories for analysis. Flow cytometry results were available for all specimens. Results from the newly established FISH laboratory in Eldoret, Kenya were cross-validated in Indianapolis, Indiana.

Results: Concordance studies found 18 of 19 (95%) of specimens studied yielded analysable FISH results for one or both probe sets (MYC and MYC/IGH) in both locations. There was 94% (17/18) concordance of results between the two FISH laboratories. FISH results were 100% concordant for the 16 specimens with a histopathological diagnosis of BL and two of three non-BL cases (one case no result in IU FISH lab). FISH was similarly concordant with flow cytometry for specimens with positive flow results with the exception of a nasopharyngeal tumour with positive flow results for CD10 and CD20 but was negative by FISH. The modal turn-around time for FISH testing on retrospective study specimens performed in Kenya ranged between 24 and 72 hours.

Conclusion: FISH testing was established, and a pilot study performed, to assess the feasibility of FISH as a diagnostic tool for the determination of BL in a Kenyan paediatric population. This study supports FISH in limited resource settings to improve the accuracy and speed of diagnosis of BL in Africa.

Keywords: Burkitt lymphoma; FISH; MYC rearrangement; MYC/IGH translocation; fluorescence in situ hybridisation.

Figure 1.. Tumour from MBL-019: abdominal mass, core biopsies. Sections show a tumour composed of sheets of intermediate cells with scant cytoplasm, irregular hyperchromatic nuclei, inconspicuous nucleoli and brisk mitotic activity. Focal area exhibits a ‘starry sky’ appearance. Morphologic features consistent with BL.

Figure 2.. FISH on interphase nuclei with the t(8;14) and MYC break apart probes. The left upper corner demonstrates a normal FISH pattern (left) for the t(8:14) with RRGGAA. Red = MYC, Green = IGH and aqua (A) is the chromosome 8 centromere. The right upper corner is the abnormal dual fusion signal pattern representing a t(8;14). The lower panels show a normal MYC break apart probe pattern (fusion/fusion signal pattern) on the left and a rearrangement pattern RGF on the right.