pancytopenic phase(pre - all ) associated with a hypocellular or normocellular bone marrow may precede the diagnosis of acute lymphoblastic leukemia(all ) . there have been several reports about names to describe this condition , usually in childhood , which include aleukemic prodrome , preleukemic all , aplastic presentation of all , hypoplastic preleukemia . there are also several reports that present the pathogenesis of pre - all and conclude that the pre - leukemic aplasia in childhood is a feature of all . only a few reports about the pathogenesis of adult pre - all have been published , it may be difficult to distinguish adult pre - all from aplastic anemia or hypoplastic myelodysplastic syndrome and , actually , the patients are often treated as if they had hypoplastic anemia . we discuss several possibilities such as myelodysplastic syndrome , primary bone marrow lymphoma , pre - all and primary aplastic anemia , and  primary unknown metastatic lymphoma of bone marrow  as the causes of proceeding pancytopenic phase with or without a few circulating blasts in adult all . two adult cases of acute lymphoblastic leukemia , which had previously a course of hypoplastic anemia , were finally diagnosed according to fab criteria in the hematology department of kyungpook university hospital . a 41-year - old man presented in may 1994 with severe anemic symptoms of recently aggravated dyspnea and dizzness . he did not have any history of drug medication , hemolytic disease and previous illness . the initial complete blood count showed hb 4.7g / dl with 1.3% reticulocytes , wbc 1.210/l with a differential of 36% neutrophils , 60% lymphocytes , 4% monocytes and platelet 5510/l . laboratory results showed serum iron level ( 287 ug / dl : normal range ; 35150 ug / dl ) tibc ( 352 ug / dl : normal 260400 ug / dl ) ferritin ( 461 ug / l : normal 20400 ug / l ) , erythropoietin ( 307 mu / ml : normal 1025 mu / ml ) . given the concern that this clinical picture could represent anemia of bone marrow failure , two bone marrow aspirates and biopsies were performed . one was a dry tap and the other aspirate showed a scanty marrow particle with a few lymphoid cells ( fig . 2 ) with many t - lymphoid cells stained by monoclonal pan - t cell antibody . because we wondered where a few abnormal cells in bone marrow aspirate are from , ct scan and tumor seeking scans , including ti-201 , ga-67 , mibi scan , were checked to find out lymphatic mass which might exist somewhere in the body . all imaging studies were negative except the bone scan showed small hot uptake in right knee area . the patient was maintained with low dose steroid and decadurabolin injection for presumed aplastic anemia . three months after initial presentation , his cbc showed normal counts and he was well for 3 months . after that , he again manifested more severe pancytopenia for 6 months ( table 1 ) . bone marrow studies during the second six months also showed hypocellular marrow with a few abnormal lymphoid cells . chest ct scanning showed homogenous , irregular margined soft tissue mass in the antero - superior mediastinum and mass lesion encasing the right - sided bronchus(fig . bone marrow aspirate at this time showed infiltration with pas positive lymphoblasts ( 73.4% ) . a diagnosis of all was made and adriamycin - vincristine - prednisolone therapy was started , but he died of sepsis and respiratory failure six days later . a 20-year - old lady presented with easy fatigability , dizziness and menorrhagia of one month duration . physical examination revealed no organomegaly and lymphadenophathy . a routine blood count revealed : hb,5.4 g / dl with 1.1 % reticulocytes ; wbc , 2.210/l with 34 % neutrophils , 56 % lymphocytes , 6 % monocytes and 4 % blast like cells , platelet count , 1410/l three bone marrow aspirates at different sites revealed dry tap and the bone marrow biopsy showed normocellular marrow with some dysplastic cells . the t2-weighted image of spine mri in pancytopenic phase showed relatively high signal in the marrow suggesting  reconversion  rather than diffuse marrow disease with tumor cell infiltration ( fig . after six week well - being period , she presented again with fever and arthralgia . immunophenotyping study showed the blasts were lymphoid lineage , pre - b ( cd10:68.7% , cd19:94.9% , cd22:93.3% ) or pre - b with some cd33 ( myeloid ) , cd34 ( stem cell ) activity . a diagnosis of all l2 was made at this time and she has been in complete remission for 4 months after having five serial chemotherapeutic cycles with adriamycin- vincristine- prednisolone and intrathecal chemotherapy with methotrexate for cns prophylaxis . preleukemic states characterized by pancytopenia and bone marrow hypoplasia are widely recognized in adults with nonlymphocytic leukemia , but have rarely been associated with adult all . the aplastic phase ( pre - all ) in children is transient and remission may be spontaneous or rapidly induced by corticosteriod . this type of presentation is observed in about 1.32.2 % of pediatric all . recently , there has been a report saying aplastic presentation as pre - leukemic state of all should be suspected not only in children but also in adults . we observed the adult pre - all patient ( case 1 ) who had pancytopenia at presentation , a subsequent recovery phase , and finally terminal all one year after initial presentation . possible explanations have been proposed for the pathogenesis of an aplastic presentation ( pre - all ) : 1 ) an exogenous factor ( infection or toxic agents ) that causes the bone marrow depression and simultaneously a mutation of a hematopoietic stem cell transforming it into leukemic cell ; 2 ) the presence of endogenous corticosteroids in quantities sufficient to temporarily eliminate lymphoblasts ; 3 ) the existence of a clonal disorder with a true preleukemic state ; 4 ) the possible inhibitory properties intrinsic to the leukemic cells rather than to other host factors ( paraneoplastic syndrome ) . the spontaneous recovery may be explained by the development of resistance to the putative inhibitory factor by the normal hematopoietic progenitor cells or neoplastic cells losing their inhibitory properties as a result of further clonal evolution ; 5 ) folate deficiency in all . folate deficiency status in ill patients is known to produce rapidly developing pancytopenia and actually folate status may contribute to the aplastic phase in all . we wondered where a few abnormal lymphoid cells , resembling a lymphoma cell , a bit , seen in bone marrow aspirate of case 1 were originated from . several scenario about pathogenesis , besides pre - all , may be possible in this case . first , primary bone marrow lymphoma which cells were initially indolent within 1 year . in this hypothesis , pancytopenic phase may be due to the myelophthisic or paraneoplastic effects of lymphoma cells on normal hematopoietic system . unknown primary metastatic lymphoma of bone marrow  , which is an unfamiliar diagnostic terminology , may be possible as the pathogenesis in patients who have pre - all like manifestations . all possible studies , including tumor seeking scans , whole body ct , serologic marker studies in our case to seek an occult lymphatic mass which might exist , were negative . it might be possible that indolent metastatic lymphoma in bone marrow had myelophthisic impacts and finally transformed into highly aggressive lymphoma / leukemia . at the time of all phase in our case , he eventually manifested a mediastinal mass that has been the origin of some lymphoid cells in bone marrow observed at initial presentation . third , the developing leukemia , often within a few months following aplastic anemia , might in fact have had a hypocellular myelodysplastic syndrome . we also were not able to get marrow particles in case 1 , even though we tried to aspirate bone marrow particles from three other aspiration sites . in patients showing a few lymphoid cells in bone marrow , the possibility of pre - all must be taken into consideration for diagnosis and the mri of bone marrow may be helpful for guessing what kind of disease is progressing in bone marrow . strictly , case 2 may not be an aplastic one and , otherwise , may be a familiar picture of all presenting as pancytopenia with few circulating blasts temporarily . one author reported on terminology relating to pre - all that the prodrome could more usually be described as aplastic. the pancytopenic phase observed for 6 weeks in case 2 may represent a preleukemic phase of all which is applicable to myelodysplastic syndrome , preleukemic phase of aml . it may be confusing to do differential diagnosis between myelodysplastic syndrome and primary aplastic anemia in a case like this . hypercellular marrow and reticulin fibrosis in the bone marrow biopsy may help to distinguish pre - all from aplastic anemia . it is impossible to determine the effect of the preleukemic state upon long - term prognosis of the leukemic process . aplastic presentation ( pre - all ) with or without abnormal lymphoid cells within the bone marrow , followed by later development of all , must be differentiated from primary aplastic anemia and myelodysplastic anemia , especially in adults . in addition , primary bone marrow lymphoma and  primary unknown metastatic lymphoma of bone marrow  may be possible as the pathogenesis in pre - all
we report two cases of adult acute lymphoblastic leukemia presenting with preleukemic phase of pancytopenia with a few abnormal lymphoid cells in bone marrow aspirates . 
 the initial diagnosis of each case was suspicious aplastic anemia and hypoplastic anemia . 
 both cases progressed to overt acute lymphoblastic leukemia within 1 year . 
 we suggest that initial pancytopenic phase ( pre - all ) may precede the diagnosis of acute lymphoblastic leukemia in adults and differential diagnosis from myelodysplastic syndrome and primary aplastic anemia will be needed . 
 we also suggest that primary bone marrow lymphoma and  primary unknown metastatic lymphoma of bone marrow  may be possible as the pathogenesis in a case like ours .