Case 316 Ryan Johnson, MD; Athena Cherry, PhD; Dita Gratzinger, MD, PhD Stanford University Medical Center SH-EAHP October 24, 2013

41F - ED presentation Periodic heart palpitations x several weeks Increased bruising x several months CBC on admission WBC: 82.9 x 10 9 /L Platelet: 24 x 10 9 /L Hgb: 6.0 g/dl Manual differential Neutrophils: 18% Basophils 3% Myelocytes: 17% Metamyelocytes 6% Promyelocytes 38% Blasts 7% Lymphocytes 11%

Morphologic review Neutrophils with pseudo-Pelgeroid nuclei and a subset with hypogranular cytoplasm Platelets decreased but morphologically normal No absolute increase in eosinophils, basophils, or monocytes Erythrocytes decreased but unremarkable Trephine was insufficient for analysis Bone marrow aspirate was submitted for flow cytometry

Bone marrow aspirate Blasts 1% Promyelocytes 9% Myelocytes 28%* Metamyelocytes 20% PMNs 34%* erythroids 4% lymphs 2% plasma cells 1% monos 1% Blasts without Auer rods or granules (some with perinuclear hofs) Subtle increase in eosinophils Neutrophils with pseudo-Pelgeroid changes Erythroids and megakaryocytes were unremarkable in morphology

Flow cytometric analysis Limited panel was performed due to the low blast count

Flow cytometric analysis CD56 CD34 CD13 CD19

Flow cytometric analysis CD56 CD34

Flow cytometric analysis Blasts (1.2% of CD45+ events) with expression of CD34, CD33, CD38, aberrant expression of CD19 (partial) and CD56, and lacking expression of CD10 and CD20 Majority of events (91% of CD45+ events) present in granulocyte region of high SSC/CD45 base plot Monocytes with aberrant expression of CD56

Differential diagnosis Atypical CML, BCR-ABL negative MPN-U (chronic neutrophilic leukemia) Leukemoid reaction Additional studies BCR-ABL FISH negative for BCR-ABL rearrangement (dual color, dual fusion probe) BCR-ABL PCR (real time PCR) Also negative Mutational studies Negative for NMP1 insertion, FLT3 D835 mutation or FLT3 ITD, JAK2 V617F, CEBPA, and exon 8 or 17 of c-KIT

Chromosome analysis - 21/21 cells

RUNX1-RUNX1T1 fusion probe

Interphase FISH revealed 88% of nucleated cells possessed RUNX1- RUNX1T1 fusion Presumably present in mature granulocytes Refined diagnosis (oligoblastic) Acute myeloid leukemia with t(8;21) CONSENSUS DX: Oligoblastic acute myeloid leukemia with t(8;21)(q22;q22)RUNX1-RUNX1T1

Frequency of oligoblastic AML with t(8;21) Rare Review of Stanford cases – 1 of 84 Experience similar in other series of t(8;21) AML Estey et al (Hematol Pathol 1992) – 1 of 50 cases Recommended that patients managed similarly to AML with blast counts >20%

Outcomes in Oligoblastic AML with t(8;21) – Adults Kaneda et al (Eur J Hematol 2002) “MDS with t(8;21)” (12) vs. t(8;21) AML (43) Avg blast count for t(8;21) MDS 7.5% (range ) 5 cases with <5% blasts No difference in (abs) WBC, CBC, platelet counts Abs. count of events past promyelocyte stage higher in oligoblastic AML Expression of CD19 and CD56 in approx. half of cases 9 of 12 oligoblastic AML and 42 of 43 cases of t(8;21) AML received Ara-C + anthracyline No significant difference in frequency of CR, rate of relapse, or overall survival in both groups with t(8;21)

Patient follow-up Initially managed with 3+7 followed by 4 cycles HiDAC Day 14 marrow showed a treated marrow with 2% blasts and FISH positive for RUNX1-RUNX1T1 Day 60 marrow showed no morphologic evidence of disease and FISH was negative 2 years out with normal hematologic parameters