PO05 - Latent acute promyelocytic leukemia can cause disseminated intravascular coagulation a month before morphological and cytogenetic diagnosis.

Background: Disseminated intravascular coagulation (DIC) is almost inevitable in acute promyelocytic leukemia (APL) at initial presentation, but there have been few previous reports on how early the complication has been present.

Aims: The purpose of this study was to clarify when DIC associated with APL really appeared, using hematological data and immunohistochemical methods based on our experienced clinical case.

Methods: Based on the hematological and bone marrow immunohistochemical findings of a case of DIC of unknown cause, we elucidated the pathogenesis of the disease to achieve our objective.

Results: [Case of origin] A 70-year-old female referred for bleeding symptoms. Her peripheral blood showed severe coagulopathy with low coagulation factor and elevated fibrinolytic markers, suggesting hyperfibrinolytic DIC. Bone marrow (BM) puncture revealed CD68 positive scattered histiocyte-like cells with normal karyotype and absent immunoglobulin gene rearrangement, indicating no definite evidence of leukemias or lymphomas. Anticoagulation by soluble human recombinant thrombomodulin and chemotherapy for malignant tumors of the histiocytic system did not improve DIC. On 32nd day of the chemotherapy, a second BM puncture revealed promyelocyte proliferation. G-band: 46,XX,t(15;17)(q24;q21)[17]/46,XX[3], PML::RARα mRNA: 57x104Copy/μL, and diagnosed with APL. DIC improved quickly with induction therapy with ATRA, and BM FISH analysis at the initial visit confirmed t(15;17) at 67/200 cells later.
[Cell Biochemistry] Annexin-2 Antibody (SABⓇ) was used to stain BM puncture smears from the initial diagnosis to remission phase. Staining was strongly positive one month before diagnosis and diminished with remission induction therapy.

Conclusion(s): [Discussion] Our case demonstrated initiation of APL may show the absence of morphological and chromosomal abnormalities that showes DIC of unknown cause or refractory to chemotherapy.
[Conclusion] Latent APL can be complicated with DIC 1 month before the morphological and cytogenetic diagnosis by G-band analysis and it is important to observe progress later.