Aplastic anaemia evolving into myelodysplastic syndrome.

Acquired aplastic anaemia is a clonal disorder of multifactonal origin. The ~pathophysiology of this disorder is still not clear Presumably the multiple incriminating factors include an intrinsic derangement of haematopoiesis, immune mediated damage to bone marrow and genetic predisposition. The long term complications of the aplastic anaemia include clonal evolution into disorders like Paroxysmal Nocturnal Haemoglobiniiria (PNH), Myelodysplastic Syndrome (MDS) and Acute Non-Lymphoblastic Leukaemias (ANLL) seen especially in non-grafted cases. These clonal changes are usually seen in the patients who receive immunosuppressive therapy e.g., ALG with or without cyclosporin and corticosteroids. The MDS cases evolving from aplastic anaemia have shown chromosomal aberrations similar to those seen in secondary MDS e.g., trisomy, monosomy, monosomy 5, del 5q and del 7q etc. This suggest that clonal evolution is the result of therapy, although the mechanism is not clear. It is extremely unusual to see clonal evolution in patients of aplastic anaemia who recoverspontaneously orwiththe use of androgemc steroids or have been transplanted. Some of these cases are probably hypoplastic MDS or hypoplastic ANLL right from the beginning. Such cases deteriorate rapidly and die within a short time. We report a case ofaplastic anaemia who was treated only with androgens and recovered. After a period of six years, during which he remained almost symptom free, he eventually developed Chronic Myelomonocytic Leukaemia (CMML).