Spectrum of Myelodysplastic Syndrome in Patients Evaluated for Cytopenia(s) in a Single Institute in Saudi Arabia

Background: Myelodysplastic syndrome (MDS) is a clonal disorder of hemopoeitic stem cells, characterized by ineffective hematopoiesis, peripheral cytopenias along with hypercellularity of marrow and dysplastic features. Establishing MDS diagnosis is difficult due to nonspecific clinical presentation and imprecise morphological criteria. In anticipation to improve the clinical practice in this field, we aimed to characterize the clinical and morphological features of MDS and non-MDS cases presented with cytopenia(s).

Methods: We reviewed all cases referred to the hematology labat KFSH-RC Hospital, Riyadh, Saudi Arabia, for cytopenia(s) to rule out MDS between January 2009 and March 2016.

Results: N= 176 patients (155 adults and 21 children). Among the adult cases, MDS was confirmed in 82 (52.9%), M:F is 1.6:1 with a mean age of 50. MDS subtypes were as follow, MDS-SLD8.4%, MDS-RS-SLD 7.3%, MDS-MLD 20.7%, MDS 5q 2.4%, MDS-U 7.3%, MDS-EB-119.5%, MDS-EB-2 28%, t-MDS 6.1%. The dominating cytogenetics abnormalities were monosomy 5 and monosomy 7 which were found in 20.7% and 24.4% of the cases respectively. Peripheral cytopenia(s) not due to MDS was found in 54 (34.8%) cases, M:F is 1:1 with a mean age of 43. The causes of cytopenia(s) were as follow, Bone Marrow Failure 22.2%, peripheral destruction in 20.3%, Drug induced in 20.3%, Anemia of chronic disease in 16.6%, B12 deficiency in 7.4%, infection in 7.4%, PNH in 3.7%, ICUS in 1.8%, IDUS 1.8%. Definite diagnosis of MDS was not possible in 19 cases due to insufficient clinical data. Comparing MDS to non-MDS group, MDS patients had Hb ≤ 90g (P-value <0.001), dysplasia in the peripheral blood neutrophils 84.9% compared to 15.1% (P-value <0.001),and dysplastic megakaryocytes in the trephine biopsy 83.3% compared to 16.7% (P-value <0.001). Inchildren, MDS was diagnosed in 8 cases (38%) with a mean age of 3.7 and male to female ratio was 3:1. Three cases diagnosed as Refractory Cytopenia of childhood (RCC) and five cases as (REAB-1). Cytopenias due to other causes was diagnosed in 8 patients (38%) with a mean age of 6.5, M:F ratio 1.6:1. The causes of cytopenia(s) as follow, 4 due to bone marrow failure, 2 due peripheral destruction, 1 due to immune deficiency, 1 due to viral infection. Definite diagnosis cannot be made on 5 cases.

Conclusion: MDS is the cause of cytopenia(s) in a significant number of patients, appeared at younger age, and tends to be more aggressive compared to international studies. Anemia, dysplastic neutrophils in the peripheral blood, and dysplastic megakaryocytes in the bone marrow trephine biopsy are the most reliable features in distinguishing MDS from an alternative diagnosis.