Myelodysplastic Syndrome (MDS)
Introduction
A collection of clonal disorders affecting
hematopoietic stem cells. It is characterised by
dysplastic changes in one or more lineages and ineffective hematopoiesis.
Etiology
De novo origin or following exposure to toxins
(including certain chemotherapeutics), ionizing radiation or
association with some hematological diseases
(for example Fanconi anemia).
Clinical signs
- age: primarily elderly patients (median is 70 years of age)
- incidence 3/100.000, 20/100.000 among 70-year olds
- anemia — weakness, paleness, dyspnoea
- neutropenia — opportune infections
- thrombocytopenia — increased susceptibility to bleeding
Classification
WHO 2008:
- Refractory cytopenia with unilineage dysplasia (RCUD)
- Refractory anemia with ringed sideroblasts (RARS)
- Refractory cytopenia with multilineage dysplasia (RCMD)
- Refractory anemia with excess blasts (RAEB)
- MDS with isolated 5q deletion (5q-syndrome)
- MDS unclassified (MDS-U)
Histology
- Structural features:
- bone marrow is usually hypercellular
- distorted architecture:
- clusters of megakaryocytes
- peritrabecular erythropoiesis
- dispersed erythropoietic islands
- ALIP (abnormal localisation of immature precursors)
myelopoiesis phenomena
- Cytological features:
- megakaryocytes: hypolobated or hyperlobated nuclei,
hyperchromia, micromegakaryocytes
- erythropoiesis: megaloblastic changes, bizzare nuclear shapes,
nuclear budding, internuclear bridges, polynucleated cells,
cytoplasmic vacuolization, ringed sideroblasts
- granulopoiesis: nuclear hypolobation (pseudo–Pelger-Huet anomaly),
nuclear hypersegmentation, hypogranular cytoplasm
