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spontaneous remission ( sr ) in the course of acute myeloid leukemia ( aml ) is observed very rarely . till now
, about 100 cases among adult patients have been reported in the literature , especially in the previous century .
one of the explanations of this fact is that effective chemotherapeutic strategies have become widely available and are introduced just after establishing the diagnosis .
currently , only a small group of patients ( advanced age , poor performance status , presence of severe comorbidities ) disqualified from intensive , potentially curative treatment , or who refused such treatment , can present sr . the mechanisms of sr remain unclear but their association with preceding transfusions of blood components and severe systemic infections has been reported . in this paper
we report the first , to our best knowledge , case of a polish adult patient with aml who had spontaneous remission .
a 77-year - old man suffering from fatigue , dizziness and mild weight loss , which started in august , 2011 , was admitted to hospital in september , 2011 .
evaluation of peripheral blood ( pb ) and bone marrow ( bm ; 22 september , 2011 ) showed 16% blasts in pb and 82% in bm smear .
based on cytomorphology , cytochemistry and also on immunophenotyping , the diagnosis of acute myelomonocytic leukemia was established .
cytogenetic analysis showed the 48 , xy , + 13 , + 21/46 , xy karyotype in 17/20 observed metaphases , which qualified the patient to the cytogenetic intermediate risk group .
the patient did not receive intensive chemotherapy due to his performance status and presence of cardiological and neurological comorbidities , and was qualified only to the best supportive care . in this time
he was treated with non - irradiated red cell transfusions ( 4 units ) and low - dose corticosteroids ( methylprednisolone 24 mg / d ) . during the whole hospitalization
there was only one short episode of non - infectious diarrhea observed . in november , 2011 treatment in a clinical trial with 5-azacytidine
was considered and , therefore , laboratory tests , pb and bm smear evaluation , flow cytometry of bm , and cytogenetics were repeated . laboratory tests showed only moderate leukopenia ( wbc 3.39
cytogenetic analysis revealed the same aberrations as those present at the onset of the disease .
cytomorphologic and immunocytometric evaluation of pb and bm indicated improvement : 4% of blast cells in bm and presence of many cells in destruction were observed .
the corticosteroids were stopped and 2 weeks later tests were repeated . the complete blood count became normal , with hb 7.8 mmol / l , wbc 4.54 g / l , and platelet count of 165.0
repeated cytologic and immunocytometric evaluation of pb and bm showed complete hematological remission ( 25 november , 2011 ) . also histological evaluation of bm confirmed resolution of aml , showing fatty marrow with poor cellularity and few groups of immature cells ( less than 5% ) . the patient was closely monitored during the following months and he remained in spontaneous hematological remission until may , 2012 .
based on peripheral blood and bone marrow evaluation on 29 may , 2012 a relapse of aml was recognized .
the patient and his family declined intensive treatment because of his bad performance status and palliative treatment consisting of hydroxyurea , 6-mercaptopurine and the best supportive care was provided .
on 12 august , 2012 he was admitted to hospital with symptoms of septic shock . in spite of intensive treatment he died 6 hours after admission .
spontaneous remission has been reported for adult t - cell leukemia / lymphoma , chronic lymphocytic leukemia , chronic myelogenous leukemia , myelodysplastic syndrome , acute lymphoblastic leukemia and also acute myeloid leukemia [ 26 ] .
after that time only a few case reports of sr were published . between 1979 and 2008
the median duration of remission was generally short ( the mean was about 6 months ) ; however , even long - term and complete cytogenetic remissions were documented [ 9 , 10 ] .
the mechanisms of sr still remain unclear but it is often triggered by severe , especially bacterial , but also viral or fungal infections .
the explanation of this phenomenon is that infections could lead to exuberant activation of the immune system and could exert an anti - leukemic effect causing containment of the leukemia . in severe infections a profound increase in levels of cytokines such as tumor necrosis factor  ( tnf- ) , interleukin 2 ( il-2 ) and
interferon (ifn- ) as well as increased antibody - mediated cytotoxicity of nk and activity of cytotoxic t cells and macrophages were observed [ 13 , 15 , 16 ] .
it was also reported that cytomegalovirus ( cmv ) reactivation , in some conditions , could elicit  t cells which were able to cross - recognize both cmv - infected cells and primary leukemic blasts .
some authors suggested that cmv could have an antileukemic effect by infecting cd33-positive hematopoietic progenitors .
however , this hypothesis was not supported by other authors . additionally , infections are frequently accompanied by hypergammaglobulinemia [ 11 , 20 ] .
an adverse transfusion reaction might have also played some role in the occurrence of spontaneous remission .
transfusion - associated graft versus - host - diseases ( ta - gvhd ) and graft - versus leukemia ( gvl ) reaction were observed after transfusion .
such anti - leukemic effects might stimulate remission of aml , especially in patients treated with non - irradiated blood products .
however , at present , nearly all aml patients receive leukocyte - depleted transfusions , which highly reduces probability of the above - mentioned reactions .
infections and/or blood transfusions are postulated as the main causes of sr but there were also patients with sr reported who had neither infections nor transfusions .
other factors which might play a role in sr of aml are corticosteroids or colony - stimulating factors ( csf ) .
although in some cases of sr the administration of corticosteroids was described , a review of the literature shows that there is no evidence that steroid treatment is able to induce remission in aml [ 22 , 23 ] .
it is well known that in biphenotypic leukemia , which is partially responsive to steroid treatment , remission might be misinterpreted as a case of sr .
maturation of leukemic cells was reported to be induced in vitro by colony - stimulating factors [ 24 , 25 ] .
some authors even speculated that severe infections might cause an augmented release of hematopoietic growth factors ( granulocyte or granulocyte - macrophage csf and/or other ) that results in transient overgrowth of leukemic cells , leading to further maturation and differentiation . in this paper
we present a patient with acute myelomonocytic leukemia . acute myeloid leukemia with myelomonocytic / monocytic differentiation represents the largest group of reported cases [ 9 , 10 ] .
because of deep anemia he was treated with non - irradiated , non - leukocyte depleted transfusions ( in a local hospital ) .
therefore , a potential ta - gvhd / gvl might lead to spontaneous hematological remission .
however , we did not observe clinical symptoms of such reactions apart from a short episode of non - infectious diarrhea .
additionally , steroids were administered but their role in inducing sr , in our opinion , seems less probable .
spontaneous remission ( sr ) of acute myeloid leukemia ( aml ) in adults is observed very rarely . to date 
 , about 100 cases have been presented in the literature . to our best knowledge , 
 we describe the first adult polish patient suffering from acute myelomonocytic leukemia ( 48 , xy , + 13 , + 21/46 , xy ) , in whom after supportive therapy , including non - irradiated , non - leukocyte depleted red cell transfusions and low - dose corticosteroid , we observed resolution of the disease without cytogenetic remission . 
 we suggest a potential transfusion - associated graft versus - host - diseases ( ta - gvhd ) and graft - versus leukemia ( gvl ) reaction which might lead to spontaneous hematological remission . 
 however , we did not observe clinical symptoms of such reactions apart from a short episode of non - infectious diarrhea . 
 additionally , steroids were administered but their role in inducing sr , in our opinion , seems less probable . 
 this 77-year - old man remained in sr for 7 months , when repeated analysis showed aml recurrence . 
 he died due to septic shock 2.5 months later . 
 additionally , we present a review of the literature .