Laboratory presentation and diagnosis of mds

acute leukemia, the French-American-British (FAB) group acknowledged that not all patients with cytopenias and dysplastic peripheral blood and bone marrow features progress to acute leukemia. A distinction was made between acute leukemia with its rapid onset of signs and symptoms requiring immediate treatment and c group of disorders that showed some of the characteristics of AML but were either sub-acute or chronic in nature. The FAB group chose the term dysmyelopoietic or myelodysplastic syndromes for this group of disorders, as unlike AML, immediate treatment was rarely needed and these patients were typically 60 years of age or older. Initially, the FAB group recognized two categories of MDS: RAEB and chronic myelomonocytic leukemia (CMML). Investigators noted that a  variable progression of these cases evolved to overt acute leukemia associated with an increase in blasts to approximately greater than 30%. In 1980, a larger number of cases were reviewed with the intent to determine if specific morphological abnormalities, singly or in groups, would predict for a different biological outcome. This larger review of cases led to an expanded definition of the  MDSs into five subgroups that could be characterized by dysplastic features noted above.

LABORATORY PRESENTATION AND DIAGNOSIS OF MDS

A diagnosis of MDS should be entertained particularly in an elderly patient (the peak incidence is in the eighth decade of life) in the setting of an unexplained anemia, neutropenia. thrombocytopenia and/or monocytosis without the usual explanations of marrow failure. Anemia (hemoglobin < 11 g/dL) is most common (typically isolated), but occasionally isolated thrombocytopenia and even less commonly isolated neutropenia have been noted. Isolated thrombocytopenia may precede b\ 2 to 10 years. the development of the features to be discussed below that permit classification as MDS. Another challenge to the clinician confronting a potential case of MDS is that, occasionally, the patient will not present with a cytopenia The presentation can be one of leukocytosis particular!) in association with CMML or one of thrombocytosis particularly in association with RA or RARS (in turn in association often with partial deletion of the long arm of chromosome no. 5 termed 5q -).

The diagnosis of MDS can only be made after careful examination of the peripheral blood  smear, bone marrow aspirate, and biopsy specimen. No single morphological finding is diagnostic. rather, the combination of dysplastic features in the peripheral blood and bone marrow is necessary. The diagnosis of MDS is a diagnosis of exclusion, in particular the following always must be excluded as they can be accompanied by dysplasia: (1) vitamin B12; and/or folate deficiency; (2) proven exposure to heavy metals: (3) recent cytotoxic therapy: (4) ongoing inflammation including HIV and cancer, and (5) chronic liver disease/alcohol use.

The first three criteria should be considered absolute exclusions precluding the definite diagnosis of MDS whereas the latter two could be considered to be relative exclusions as patients will exist with both MDS and a coincidental inflammatory state (such as cancer or rheumatoid arthritis) or MDS with coincidental chronic liver disease/alcohol use. Furthermore, even after ruling out the above conditions, the diagnosis of MDS can be elusive due to its variability'¹ with regard to (1) sampling site (sternal versus iliac); (2) cellularity (differences may be noted within adjacent spaces