[Drug-induced bone marrow changes]

Cytomorphological and histomorphological analysis of bone marrow cells in cases with abnormal production of blood cells must always take the unwanted side effects of drugs into account. Drugs can affect single lineages or the complete bone marrow. Besides quantitative phenomena consisting of hypoplasia or hyperplasia, maturation of blood cells may be disturbed. Disturbances encompass left shifts, which may be extreme, or imitate states of vitamin deficiency and atypia occurring in myelodysplastic syndromes (MDS). In addition, all bone marrow lineages may be affected, simulating aplastic anemia. The spectrum of causative drugs is very broad, and the induced changes are generally not specific enough to identify the underlying drug culprit, which requires knowledge of the patient's drug history. Cytotoxic drugs applied in oncology can induce MDS with an average latency of 2-6 years, or even shorter in the case of drugs interfering with DNA repair.