Submitting Author: Alghamdi, Sarah Ahamd, MBBS
Institution: Mount Sinai Medical Center
Additional authors:Vathany Sriganeshan
Session: Acute leukemias of ambiguous lineage

A 63 year old woman with a medical history of hypertension, coronary artery disease, stable angina and uterine cancer, presented with complaints of night sweats, chills and abdominal pain. She was found to have marked leukocytosis.

The CBC showed: WBC: 56, RBC: 4, HGB: 11.6, HCT: 35.4, MCV:88.9, MCH:29.1, MCHC:32.8, RDW:14, PLTS:98

A posterior iliac crest bone marrow biopsy and aspirate was fixed in 10% buffered formalin.

A peripheral blood smear showed decreased platelets and numerous blasts.

The aspirate smears showed hypercellular marrow particles with decreased megakaryocytes and erythropoiesis. Numerous blasts with features of monoblasts and smaller blasts with high N/C ratio were noted. Mature monocytes are increased and scattered eosinophils are present. The differential count on the aspirate smear revealed: blasts: 65%, maturing granulocytes: 3%, erythroid: 3%, lymphocytes: 16%, monocytes: 11%, eosinophils:2%.

The bone marrow aspirate and biopsy sections revealed hypercellular marrow (95% cellular) with a markedly increased immature cell population. Cytochemical stain for Myeloperoxidase on the peripheral blood smear showed granular cytoplasmic staining in a subset of the blasts and in mature granulocytes.

TdT and PAX5 stain numerous immature cells in the biopsy.

Flow cytometry reveals a population of 60% cells is gated on the blast region. Cells within the blast region consist of two distinct populations. A population of cells with dim CD45 and low side scatter express CD34, CD19, CD10, CD33, HLA-DR, and CD38. Another population showed bright CD45 and increased side scatter and express HLA-DR, CD33, CD4, partial CD5, dim CD11B, CD14, CD64, partial CD15, and CD38.

Karyotype: 45, XX, del(7)(p15), t(9:22)(q34:q11.2). -16 [19[/46,XX[1]

FISH analysis is positive for 9 and 22 dual fusion

A good example of an acute bilineal leukemia with two distinct blast population (B lymphoid and myeloid/monocytic) with t(9;22) and additional genetic abnormalities (del 7, -16)

Acute myeloid leukemia, mixed phenotype, B cell/ myeloid (monocytic) with t(9;22) (q34;q11.2), BCR-ABL 1

Additional immunostaining performed on bone marrow biopsy sections by the conference consensus group:

MPO: Positive in large blasts, negative in small blasts
Lysozyme: Positive in large blasts, negative in small blasts
CD68: Negative

Mixed phenotype acute leukemia, B/myeloid, with t(9;22)(q34;q11.2); BCR-ABL1

Case 214