Case 216

Submitting Author: Alghamdi, Sarah Ahamd, MBBS
Institution: Mount Sinai Medical Center
Additional authors:Vathany Sriganeshan
Session: AML with recurrent genetic mutations Part II

HISTORY

85 year old man with a history of multifactorial anemia of both rheumatoid arthritis and iron deficiency. His medical history includes s/p CABG, GERD and gastric antral vascular ectasia. He came for follow up when he was found to have abnormal blood work: WBC: 8.3, RBC: 2.87, HGB: 9.1, HCT: 26.3%, MCV: 91.8, MCH: 31.9, MCHC: 34.8, RDW: 21.8, PLTS: 69, NEUT: 61%, LYMPH: 23%, MONO: 5%, NRBC: 2%, MYELOCYTES: 4%, BLASTS: 7%

DETAILS

A left posterior iliac bone marrow biopsy with aspiration was submitted in 10% buffered formalin. Aspirate smears where stained with Giemsa. Peripheral blood smears were available for evaluation. The peripheral blood smear showed decreased platelets and few blasts. The aspirate biopsy showed hypercellular marrow particles, decreased megakaryocytes, decreased erythropoiesis and numerous small to medium size blasts with high N/C ratio. There were no cytoplasmic granules or Auer rods. The differential count on the smears revealed: blasts: 93%, myelocytes: 1%, maturing granulocytes: 1%, erythroid: 4% and plasma cells: 1%. The bone marrow biopsy showed hypercellular marrow (80% cellular) with sheets of small, immature cells. Normal hematopoiesis is markedly decreased.

IMMUNOHISTOCHEMISTRY AND FLOW CYTOMETRY

Stains for CD34, CD117, and TdT stain many of the immature cells. Myeloperoxidase stains few of these immature cells. CD3,CD20, PAX5, CD5 and CD1a are negative. Flow cytometry reveals a population of cells is gated within the blast region, which variably express CD34, HLA-DR, CD117 and CD38. They are negative for all lymphoid markers as well as other myeloid-monocytic, erythroid or megakaryocytic markers (CD2, CD3, CD4, CD5, CD7, CD8, CD10,CD19,CD20, CD13, CD15, CD33, CD11b, CD14, CD64, CD71, Gly A, CD41)

CYTOGENETIC FINDINGS

46, XY (20) normal male karyotype

FISH studies (MDS panel): Negative

MOLECULAR FINDINGS

None performed

INTERESTING FEATURES

This is a leukemia with primitive undifferentiated blasts expressing only CD34, CD117, HLA-DR and CD38. Myeloperoxidase stains rare blasts, However this does not meet criteria for the mixed phenotype leukemias.

PROPOSED DIAGNOSIS

Undifferentiated leukemia

CONSENSUS GROUP: ADDITIONAL INFORMATION/STUDIES

Additional immunostains performed by the conference consensus group:

TdT: Positive in blasts
PAX5: Negative
CD3: Negative
Lysozyme: Negative
CD11c: Negative
CD33: Negative
CD117: Negative

CONSENSUS DIAGNOSIS

Acute leukemia, probably myeloid, further workup required