Submitting Author: Arias-Stella, Javier Augusto, MD
Institution: Henry Ford Hospital
Additional authors:Juan C. Gomez-Gelvez, Kristin Hunt-Karner, Koichi Maeda, Kedar Inamdar
Session: AML with recurrent genetic abnormalities Part I

45-year-old female patient came into the emergency department with fever where she was found to be septic. Clinical history revealed that patient was diagnosed 1.5 years back with acute promyelocytic leukemia (APL) at an outside institution with cytogenetics confirming presence of t(15;17) (q22;q12) at initial diagnosis. She relapsed 1 year after the initial diagnosis and was subjected to maintenance chemotherapy regimen. The patient's symptoms however did not improve over the next 3 months. So, she was subjected to another bone marrow examination at our institution (see details below). The patient died due to disease related complications one month after her last biopsy.

We reviewed the previous biopsies from outside institution (biopsy at initial diagnosis and at 1st relapse). We are in the process of obtaining these slides for submission to the workshop. We report the findings below until slides become available to us.

At initial diagnosis: Bone marrow examination performed at this initial presentation showed a hypercellular marrow (90-100%) with increased myeloblasts and promyelocytes (both of them counting for 85% of cells on differential) showing Auer rods and abnormally large azurophilic granules in the cytoplasm. Markedly decreased megakaryocytes were noted. Fluorescent in situ hybridization (FISH) was performed showing PML/RARA t(15;17) (q22;q12) rearrangement in 128 out of 200 cells. Flow cytometry analysis was fully consistent with the diagnosis of Acute Promyelocytic Leukemia.

At first relapse: Peripheral blood smear: The white blood cell count overall is normal in number, but a majority of cells (57%) have blast-like morphology that differs slightly from that seen at original diagnosis. A comparison is made to the original peripheral blood smear and while a few cells were present at diagnosis that are similar to the current specimen, we no longer see the abundance of large cells with ample cytoplasm, prominent Auer rods and bilobed morphology. The majority of cells in the current specimen have very little cytoplasm and have a more convoluted, folded immature nucleus.

No aspirate smear is available for review. The touch preparation is abundantly cellular with a monotonous population of blast equivalents with similar morphology to the peripheral blood smear, estimated at least at 74%.

Clot sections are aparticulate. The bone marrow core biopsy is nearly 100% cellular with a monotonous infiltrate of immature cells with rare preserved erythroid islands and a few intact megakaryocytes with unremarkable morphology

Bone marrow biopsy results at our institution: (the pictures are presented here)

Bone marrow biopsy: The bone marrow is hypercellular (100%) with a marked increase of immature mononuclear cells resembling blasts and promyelocytic cells. They often exhibit nuclear folds and grooves. A few cells have bilobed nuclei and some promyelocytic cells have deeply basophilic cytoplasm. Single large prominent nucleoli are also seen in many cells. Auer rods are absent. Rare small megakaryocytes are also seen.

Aspirate smears: Aspirate smears are markedly hypercellular with up to 93% blasts and blast equivalents. Immature mononuclear cells resembling blasts and promyelocytic cells are significantly increased in number. They often exhibit nuclear folds and grooves. A few cells have bilobed nuclei and some promyelocytic cells have deeply basophilic cytoplasm. Single large prominent nucleoli are also seen in many cells. Auer rods are not readily apparent. Maturing myeloid cells are significantly reduced in number.

Cytochemistry:

Sudan black B stain is positive in 98-100% of blasts.

Non-specific Esterase is negative.

Flow cytometry analysis demonstrated a myeloid immunophenotype of the blasts. The blasts and promyelocytes showed the following immunophenotype: CD34+ (bright), cyMPO+, HLA-DR+, CD13+, CD10 Neg., CD19 Neg., CD5 Neg., CD7 Neg., cyCD3 Neg., cyTdT Neg. and cytoCD79a Neg.

Fluorescent in situ hybridization (FISH) confirmed a PML/RARA t(15;17) (q22;q12) gene rearrangement in 194 out of 200 (99.0%) interphase cells evaluated. In addition, trisomy 8 was identified by FISH in 96.0% of nuclei. There were no anomalies of chromosomes 11, 16 or 21. Karyotype analysis was not performed.

PCR analysis revealed the presence of PML/RARA t(15;17)(q22;q12) bcr3 fusion transcript

FLT3 receptor mutations were not identified.

This case demonstrates the morphologic and cytogenetic evolution of an APL with t(15;17) (q22;q12).

The initial diagnostic bone marrow performed showed up to 85% blasts and blast equivalents with classic features of APL cells including bilobed nuclei, frequent Auer rods and abnormally large azurophilic granules in the cytoplasm. Flow cytometric analysis was consistent with the diagnosis of APL (HLA-DR negative, CD34 negative, CD117 bright positive, CD33 bright positive and CD13 positive).FISH cytogenetic studies revealed the presence of PML-RARA t(15;17)(q22;q12) fusion gene in 128 of 200 cells. No other cytogenetic abnormalities were reported at the time of initial diagnosis. The patient was treated with chemotherapy reaching complete remission status.

One year after her initial diagnosis, the patient presented with relapsed disease. Bone marrow biopsy performed at the time of relapse showed up to 74% blasts and blast equivalents but prominent Auer rods, azurophilic granules and bilobed nuclei were not seen. FISH studies at this time confirmed the presence of PML/RARA t(15;17)(q22;q21) fusion gene. In addition, an add(19)(q13.4) was identified by karyotype analysis. The patient was managed with maintenance chemotherapy for control of her disease.

Due to the persistence of her symptoms, the patient underwent a third bone marrow biopsy three months after her relapse. This specimen revealed markedly increased blasts and blast equivalents (93% of differential count) with nuclear folds, single large nucleoli and some bilobed nuclei and again cells with frequent Auer rods and azurophilic granules were not readily observed. Flow cytometric evaluation showed myeloid immunophenotype of blast cell with expression of HLA-DR and CD34 by the neoplastic cells, not typical of classic APL. Cytogenetic studies confirmed the clonal evolution of this case with a final complex karyotype involving PML/RARA t(15;17)(q22;q21) , and trisomy 8. The patient died due to disease related complications one month after her last biopsy.

Acute myeloid leukemia with t(15;17)(q22;q21) and atypical features.

Acute myeloid leukemia with t(15;17)(q22;q21)

Case 226