Submitting Author: Kanagal-Shamanna, Rashmi, MD
Institution: University of Texas M.D. Anderson Cancer Center
Additional authors:Tariq Muzzafar, Raja Luthra, Mark Routbort and Keyur P Patel
Session: AML secondary to myeloproliferative neoplasms and other types of disease progression in MPN

A 68 year old woman with a history of refractory primary myelofibrosis for 14 years presented with increasing peripheral blood blast counts for the past 2 years. Her treatment history included imatinib, hydroxyurea, erythropoietin, blood transfusions and prednisolone. Her symptoms of anemia and organomegaly showed significant improvement to JAK inhibitor trial (INCB018424/ Ruxolitinib/Incyte) that she received for 4 years.

CBC:

WBC: 6.7 K/uL; Hemoglobin - 6.6 g.dL; MCV: 82 fl; Platelet: 95 K/uL

Differential count - Neutrophils: 53%; Lymphocyte: 7%; Monocyte: 6%; Eosinophils: 1%; Basophils – 6%; metamyelocytes – 6% and blasts: 21%.

Peripheral blood smear – anisocytosis, poikilocytosis, polychromasia, schistocytes, tear drop cells and ovalocytes with circulating blasts, no nucleated red blood cells

Bone marrow aspiration and biopsy

Site - Left posterior iliac crest

Procedure - Formalin fixed biopsy after decalcification

Gross - 1 cm; 0.9 cm

Microscopic findings –

Bone marrow biopsy was suboptimal and showed predominantly subcortical bone. Cellularity was less than 1%. Scant hematopoeitic cells were seen with rare megakaryocytes. Bone marrow smears and touch imprint were both of limited quality. Blasts were increased (24%) which were medium size, with open nuclear chromatin, inconspicuous nucleoli and moderate amount of light basophilic cytoplasm with azurophilic granules. Auer rods were not identified.

Cytochemical stains -

Myeloperoxidase negative in blasts

Special stains –

Reticulin – No linear reticulin is identified.

Trichrome - No coarse bundle of collagen

Flow cytometric immunophenotypic findings -

26% blasts were seen that showed the following immunophenotype -

Positive: CD34, CD117, HLA-DR, CD33 (partial), CD36 (partial), CD38

Negative: CD13, CD14, CD15, CD56, CD64, CD123, CD19, CD22, CD2, CD4, CD5, CD7

Diploid female karyotype; 46,XX[20]

Current secondary AML sample –

1. Negative for t(8;21)(q22;q22); RUNX1-RUNX1T1, inv(16)(p13.1q22), t(15;17)(q22;q12); t(9;22)(q34;q11.2); ETV6-RUNX1, t(1;19)(q23;p13.3); E2A-PBX1, and t(4;11)(q21;q23); MLL-AF4 and t(6;9)(p23;q34); DEK-NUP214

2. Negative for mutations in IDH1, IDH2, JAK2, KIT, KRAS, NPM1, NRAS, FLT3 (including ITD) and CEBPA

3. Two different mutations identified in codon 201, exon 8 of GNAS gene: 2 single base pair substitutions in separate alleles or clones causing two different amino acid changes:

a. p.R201C (CGT to TGT)

b. p.R201H (CGT to CAT)

4. Variant in JAK3 gene (V722I), likely germline polymorphism

Original primary myelofibrosis specimen –

Negative for mutations in codon 617 of JAK2 and codon 515 of MPL and, BCR-ABL1 fusion transcript

Interesting feature(s) of submitted case

1. Refractory primary myelofibrosis evolving to AML while on JAK inhibitor trial

2. GNAS mutations, while common in solid tumors, are extremely rare in hematological neoplasms, and have been reported in only 3 cases of myeloid neoplasms (all in MDS) until now (N Engl J Med. 2011 Jun 30;364(26):2496-506)

3. Secondary AML with two different GNAS mutations in the same codon 201 identified in different subpopulations or alleles. Role in leukemic transformation is being investigated.

Secondary Acute Myeloid Leukemia arising from Primary Myelofibrosis

Blast phase of primary myelofibrosis: acute myeloid leukemia with GNAS R201C and R201H mutations

Case 367