The Myelodysplastic Syndromes

From cellular morphology to molecular and epigenetic anomalies of myelodysplastic syndromes

“…The bone marrow smear analysis allows for determination of bone marrow cellularity and architecture with detailed evaluation of cellular morphology and evaluation of percent blasts. Three types of myeloblasts are described in MDS: one with variable size, without any azurophilic granules or Auer rods; a second one slightly larger containing 1‐20 azurophilic granules; and a third one containing more than 20 azurophilic granules with a basophilic cytoplasm and the absence of the Golgi zone . The threshold of number of blasts in the marrow for MDS is less than 30% in the French, American, and British (FAB) classification system and less than 20% in the latest WHO classification .…”

“…FAB classification is based on the study of the blood and bone marrow smears stained with Wright‐Giemsa (May Grunwald‐Giemsa in French Countries) and Prussian blue to reveal the iron content of marrow and biopsy specimens. The latter staining allows characterization of the sideroblasts that are of 3 types: normal sideroblasts (15%‐50% of erythroblasts) with 1‐4 cytoplasmic iron‐containing granules (CICG), abnormal type II sideroblast with 5‐10 CICG scattered throughout the cytoplasm, and abnormal type III sideroblast with more than 10 CICG covering at least one‐third of the nuclear rim or forming a complete ring around the nucleus (Table ). To diagnose MDS, other special stains might be used such as myeloperoxidase, Sudan black B, periodic acid‐Schiff, and specific and nonspecific esterase.…”

“…One major cause of genomic instability is telomere attrition and dysfunctional telomeres. Indeed, telomeres are critical for the maintenance of normal hematopoiesis . Hematopoiesis requires pluripotent stem cells, differentiated progenitor and precursor cells, supportive stroma, adipose tissue, vascular structures, and extracellular matrix to maintain steady state levels of the blood cellular components .…”

“…The name of MDSs is etymologically derived from the Greek word meaning morphological abnormality of the bone marrow . Because of different forms of cytological presentation of the bone marrow, MDS was previously designed as smoldering leukemia, preleukemia, and oligoblastic leukemia reflecting the diversity of clinical presentations …”

“…The incidence of MDS is about 3‐5/100 000 people with a male predominance, but its defined genetic entity del(5q)‐MDS has a female predominance . MDS is one of the most common hematologic malignancies in western countries with an overall incidence of 3.5‐12.6/100 000/year, which occurs principally in older populations with a median age of 70 years at diagnosis, which increases to 50/100 000 people in this latter category of the population . However, MDS has been reported in younger populations in Asia with a mean age of 53 years …”