myelodysplastic syndromes ( mdss ) represent a group of clonal hematological disorders characterized by progressive cytopenia reflecting defects in erythroid , myeloid and megakaryocytic maturation .
anemia , neutropenia and thrombocytopenia , separated or in combination , despite a hyper- or normocellular marrow define mds .
hypoplastic mds ( h - mds ) accounts for 1217% of all patients with mds .
clonality studies of mature blood cells and immature progenitors suggest that a myeloid  lymphoid stem cell might be the principal target for clonal transformation at least in a major part of mds .
an association between mds and autoimmune disorders and with chronic t - cell disorders like large granular lymphocytic leukemia ( lgl ) has been recognized and is suggestive of an abnormal functioning immune system in mds .
lymphoproliferative disorders , especially t - prolymphocytic leukemia ( pll ) developing in an h - mds patient , is extremely rare and has an aggressive course .
we are reporting a unique case of t - pll developing in h - mds , and this is probably the first case report in the literature .
a 45-year - old male was admitted with generalized weakness , palpitation , gradual weight loss and frequent syncopal attacks for more than 2 years . on examination ,
the iron profile was : serum iron  115.50 g / dl , total iron binding capacity 
177.10 ng / ml and markedly elevated b12 levels ( > 2000 pg / ml ) .
hemoglobin was 3.9 gm% , total leukocyte count was 2100 cells / cumm , platelet count was 70,000 cells / cumm and reticulocyte count was 0.8% at the time of admission .
pancytopenia [ figure 1a ] was persistent on every visit and the peripheral smear showed normocytic and macrocytic rbcs , leukopenia , hypogranular and pseudo pelger - huet neutrophils [ figure 1b and 1c ] , which were characteristic with relative lymphocytosis and no blasts in the peripheral smear ; the platelet count was reduced .
the bone marrow aspiration smears and cell block preparation showed severe hypocellularity ( < 20% for his age ) [ figure 1d ] .
sparse erythroid cells with dyserythropoiesis [ figure 2a and 2b ] , minimal dysmyelopoietic ( hypogranular and hyposegmented myeloid cells - 10% ) and dysmegakaryopoietic ( hypolobated and micromegakaryocytes [ figure 2c and 2d ] features were evident with blasts < 5% and absence of fibrosis in biopsy sections .
the possibility of aplastic anemia and hypoplastic acute myeloid leukaemia ( h - aml ) were ruled out .
a diagnosis of primary h - mds was made in the absence of chemotherapy and radiotherapy .
the patient was transfusion dependent and later started on thalidomide . on follow - up within few months , because of persistent pancytopenia , the patient was subjected for repeat bone marrow study , where the smear and section showed cellular marrow with diffuse infiltrate of mature lymphocytes ( 60% ) [ figure 3a and b ] with no evidence of improved hematopoiesis .
the neoplastic cells showed a mature t - cell immunophenotype , cd3 + , cd4 + , cd5 + , cd7 + and cd8 + , and tdt- , cd20- , cd23- , cd79a- , cd34- , bcl2- and cyclind1- , and was diagnosed as t - pll .
( d ) hypocellular marrow - cell block preparation h and e , 10 ( a ) dyserythropoiesis with multinucleation in bma .
( c ) dysmegakaryopoiesis - cell block h and e , 40. ( d ) dysmegakaryopoiesis bma ( a ) lymphoid infiltrate in bma .
the diagnosis may be difficult in h - mds if the aspirate is so sparsely cellular as to preclude cytogenetic studies .
significant clonal cytogenetic abnormalities are present in only half of all mds cases , and full karyotype analysis , which requires cells in metaphase , may not be possible because cells may be scarce or senescent .
we encountered similar problems when there was hypocellular marrow , but later , when diagnosed as t - pll , the marrow culture showed a normal karyotype .
there is growing scientific evidence supporting the hypothesis that cytogenetic abnormalities are not the initiating clonal event but are acquired during disease progression .
h - mds has yet to be shown to alter the disease course or prognosis , but some studies suggest benefit from immunosuppressive therapeutics .
it is presently unknown whether h - mds patients have a preceding , but unrecognised , phase of excessive apoptosis insufficiently compensated by hyperproliferation , or whether their disease is more related to aplastic anemia .
several years ago , in vitro studies have proven that autologous cytotoxic t - lymphocytes can exert an inhibitory effect on mds myelopoiesis .
an association between mds and autoimmune disorders and with chronic t - cell disorders like lgl has been recognized and is suggestive of an abnormal functioning immune system in mds .
but , occurrence of t - pll in h - mds is extremely rare and , possibly , this is the first case in the literature .
the immunophenotype is that of mature t - cell , which is usually cd4 + but , occasionally , can be cd8 + , which was evident in our case .
expression of cd7 helps to distinguish it from other clpds , like sezary syndrome and adult t - cell leukemia / lymphoma .
to conclude , the finding of activated and clonal t - cell population in mds is further argument for the use of immunosuppression to treat the cytopenias of mds .
 myelodysplastic syndrome ( mds ) represents one of the most challenging health - related problems in the elderly , characterized by dysplastic morphology in the bone marrow in association with ineffective hematopoiesis . 
 hypoplastic mds ( h - mds ) accounts for 1217% of all patients with mds and has yet to be shown to alter the disease course or prognosis . 
 the concept that t - cell - mediated autoimmunity contributes to bone marrow failure in mds has been widely accepted due to hematologic improvement after immunosuppressive therapy . 
 t - cell expansion is known to occur in these patients , but development of chronic t - cell disorders , especially t - prolymphocytic leukemia ( pll ) in a hypocellular mds is extremely rare , which has an aggressive course . 
 the possible explanation for the association between the two disorders is that t - pll might arise from a clonally arranged mds stem cell . 
 we report a unique case of h - mds with non - progressive pancytopenia and severe hypocellular marrow for 2 years , followed by t - pll within few months . 