acute promyelocytic leukemia ( apl ) , m3 subtype of acute myeloid leukemia ( aml ) is characterized in the majority of cases by proliferation of neoplastic hypergranlar promyelocytes and blast .
the biological and clinical heterogenicity of apl is based on the clinical presentation of the disease and various characteristics of leukemic cells at diagnosis .
patients with apl typically present with low white blood counts , peripheral blood cytopenias and coagulopathy .
we report a case of apl- hypogranular variant that poses particular diagnostic challenge because of its atypical morphology .
a 30-year - old male presented with severe anemia , bilateral subconjunctival haemorrhage and petechial skin rashes .
hematological examination showed a low hemoglobin count ( 9.0 gm% ) , total leucocyte count was markedly raised ( 80,000 cells / cu ) with predominance of promyelocytes and blasts on differential count and platelet count of 34,000 cells / cu .
coagulation studies showed prothrombin time ( pt ) to be 15.2 s , activated partial thromboplastin time ( aptt ) 27.5 s and fibrinogen 1.05
peripheral blood cytomorphology showed promyelocytes with a characteristic bilobed or reniform nucleus ; with majority of the cells either devoid of granules or contained only a few fine azurophil granules ( figure 1 ) .
the bone marrow aspirate was markedly hypercellular and frankly leukemic , 95% cells were blasts with bilobulated nucleus and fine dust like cytoplasmic granules .
molecular cytogenetic analysis by fluorescent in situ hybridization ( fish ) was used to investigate chromosomal abnormalities associated with the leukemic process and found out to be translocation of chromosome 15 and 17 , i.e. , t(15;17 ) ( figure 3 ) . 

acute promyelocytic leukemia : fish technique shows chromosomal translocation , t(15;17 ) . in view of the atypical blasts morphology , a provisional diagnosis of hypogranular variant of aml - m3v was suggested .
the patient was immediately started on all trans - retinoic acid ( atra ) and cytarabine and is progressing well after 12 months of follow up period .
this case report emphasizes the importance of a high index of suspicion for the diagnosis of acute promyelocytic leukemia , the hypogranular variant in particular .
overall , classical hypergranular and hypogranular variant constitute 58% of cases of aml in different western series , and hypogranular variant comprises 1/3 of all cases of acute promyelocytic leukemia .
both apl subtypes share a common pathogenic pathway , namely presence of t(15;17)(q21;q22 ) translocation and a similar clinical picture , namely consumptive coagulopathy at presentation ( table 1 ) .
they are responsive to differentiation therapy with all trans - retinoic acid ( atra ) and compete remission in seen in > 80% cases . quite similarly our case is progressing well after 6 months of follow of period .
grignani et al . have asserted that fish is rapid and cost - effective when compared to classical cytogenetics , to establish diagnoses for the specific translocation t(15;17 ) in apl patients
. proper diagnosis of apl is critical for two reasons : i ) anticipating complications due to disseminated intra - vascular coagulation ( dic ) and ii ) treatment with tretinoin ( all - trans - retinoic - acid ) for complete remission in about 80% of patients . 

table 1a comparison of classical hypergranular and hypogranular variant.hypergranularhypogranulardefinitionaml subtype in which maturation arrests in promyelocytic stage.clinicaldisseminated intravascular coagulation / consumption coagulopathywbclowhighnucleusround to ovalbilobedcytoplasmdensely packed large azurophilic granules , multiple auer rods , aggot cells.granules apparently absent , typical hypergranular promyelocytes exists in small numbercytochemistrymyeloperoxidase and sudan black - b strongly positiveimmunophenotypecd 33 + , cd 34/+ , cd15/+ ; cd 56/+ ; hla dr positivecd 13 + , cd 34 + , hla dr negativecytogeneticst(15;17 ) ( q22;q12 ) 
  to conclude , the therapeutic option and prognostic implication in apl - variant has made early diagnosis of paramount clinical significance .
although , the cytogenetic and immunophenotypic signature should be referred to in diagnosing apl , from the practical point of view , other parameters , such as cytomorphology and cytochemistry are still important tools for rapid recognition of apl .
 early diagnosis of acute promyelocytic leukemia ( apl ) is essential because of its associated life threatening coagulopathy and unique response to all trans - retinoic acid ( atra ) therapy . 
 the characteristic cell morphology supplemented by cytochemistry offers the most rapid means for diagnosis . 
 here we describe a rare case of acute promyelocytic leukemia - hypogranular variant that poses particular diagnostic challenge . 