Performance evaluation of Glass Slide Morphology, whole slide image and flow cytometry in diagnosis of acute Leukemia by types.

Abstract

Background : Acute leukemia (AL) is a life-threatening disease which require early diagnosis and treatment. In Tanzania, it is a challenge to make early and accurate diagnosis, in part due to shortage of haematologists and limited resources (i.e. availability of immunophenotyping). Diagnosis of AL in adults is made through glass slide morphology (GSM) interpretation only. Whole slide image (WSI) can be used at health facilities where there are no hematologists for early diagnosis. However, it’s efficacy in diagnosis of Acute Leukemia is not well established. Aim: To determine the clinical and laboratory characteristics of confirmed cases of AL and to determine performance evaluation of glass slide morphology, whole slide imaging and flow cytometry in diagnosis of acute leukemia by types. Methods: This was a descriptive, hospital based, cross-sectional study involving 115 patients with clinical and laboratory suspicion of acute leukemia from January 2019 to May 2019. Structured questionnaires were used to obtain socio-demographic and clinical data. Blood and bone marrow aspirates were collected from all participants for investigations. Romanowsky staining technique was used for peripheral smear and staining bone marrow slides. Flow cytometry (from peripheral blood or bone marrow aspirate) was performed as per European Group for the Immunological Characterization of Leukemia (EGIL) criteria. SPSS v.20.00 statistical software was used for data analysis. Chi square test was employed for categorical data while Mood’s median test was used to compare numerical data. Performance characteristics of the diagnostic tests were calculated by cross tabulation and compared in proportions. Results: A total of 115 individuals with features highly suggestive of acute leukemia were enrolled. Fifty one were diagnosed to have AL by GSM of the bone marrow aspirate, and out of these, 47/51 (92%) were confirmed to have acute leukemia by flow cytometry. Symptoms of anaemia were found in 41/47(87.2%) of patients that had been confirmed to have acute leukemia by flow cytometry, followed by fever 36/47 (76.6%) and bleeding 18/47 (38.3%). Organomegaly was a common sign in ALL; 35.7% and 21.4% of participants with ALL had splenomegaly and hepatomegaly respectively, in contrast to only 10.5% and 0% in AML. Among these patients with AL, 89% were found to have haemoglobin below 10g/dl and 39/47 (83.0%) had deranged white cell count. Monocytosis was reported in 22/47 (46.8%) by automated blood count machine. These were found to be blasts in peripheral smear. GSM was able to diagnose accurately 47/51(92%) of acute leukemia cases and gave the basis for diagnosis of acute leukemia. Both GSM and WSI showed reduced accuracy in diagnosis of acute leukemia by types. The concordance rate for GSM with flow cytometry in the diagnosis of AML and ALL was 57.9 and 81.4%, respectively. The concordance rate of WSI with flow cytometry in diagnosis of AML and ALL was 56.3% and 68.4%, respectively. Conclusion: The clinical presentation of AL is due to bone marrow failure; anaemia, bleeding due to thrombocytopenia, and infections (fever) related to neutropenia. Majority of patients with acute leukemia had low hemoglobin level, leukocytosis, thrombocytopenia and very high LDH. Morphology with good staining quality gives the basis of diagnosis of acute leukemia. GSM and WSI had low concordance when compared to flow cytometry in diagnosis of acute leukemia by types