The myelodysplastic syndromes
Classification
This is not straightforward. The French-American-British (FAB) classification divides MDS into five subtypes depending on morphological features and particularly the number of blood and marrow leukaemic blast cells. The more recent WHO system (Table 25.1) divides MDS into unilineage or multilineage dysplasia, refractory anaemia with ring sideroblasts and dysplasia with excess blasts. The FAB entity chronic myelomonocytic leukaemia (CMML) is now included in the overlap ‘MDS with myeloproliferative disorder’ category. It is likely that cytogenetic and molecular abnormalities will be increasingly incorporated into the classification; a current example is 5q− syndrome, a distinct subtype of MDS associated with a response to novel therapy and a good prognosis.
Clinical features
The diagnosis may follow a routine blood count in an asymptomatic patient. Where symptoms do occur they range from a mild anaemia to the consequences of severe marrow failure with profound anaemia, leucopenia and thrombocytopenia (Fig 25.1
