Contributed by Milon Amin, MD and Raymond E. Felgar, MD
The patient is a 61 year-old female with no significant past medical history other than resolution of a recent upper respiratory infection with antibiotic therapy. She presented with abdominal pain after a meal that quickly worsened over the next 24 hours. Initial workup for this pain included liver enzyme tests, amylase, and lipase levels, all of which were within normal ranges. A CT abdomen and chest x-ray were unremarkable. Complete blood count data are given below.
COMPLETE BLOOD CELL COUNT
PERIPHERAL BLOOD SMEAR
The patient's peripheral blood smear showed 59% blasts, as illustrated in Images 1 and 2. Samples of bone marrow aspirate were submitted for flow cytometric immunophenotypic studies and cytogenetic studies.
HISTOPATHOLOGY: BONE MARROW BIOPSY AND ASPIRATE
A prominent blast population is present on the bone marrow aspirate, accounting for 74% of cells on the aspirate differential count (Images 3 and 4). Review of the bone marrow biopsy demonstrated sheets of blasts and apparently dysplastic megakaryocytes with numerous small, monolobated forms (Images 5 and 6). These findings prompted a decision to add CD41a (platelet glycoprotein IIb/IIIa) and CD61 (platelet glycoprotein IIIa) to the flow cytometric analysis of the bone marrow aspirates, and to perform a CD61 immunostain on the biopsy.
Flow cytometric immunophenotypic evaluation of the bone marrow aspirate sample shows an abnormal myeloblast population (approximately 60% of all cells by CD34 staining) (Image 7). Specific gating on the CD34+ population alone showed that approximately 7% of the blasts may also be CD41a and/or CD61 (Image 8). However, the pattern of CD41a and CD61 staining is heterogeneous and the possibility of platelet satellitism (giving falsely positive staining) could not be entirely excluded. A summary of the overall phenotype for the majority of the blasts follows:
Parrafin section immunohistochemical stains show that the blasts are positive for CD117 (c-kit), CD34 (50-60%) and myeloperoxidase (20%). CD61 highlighted abnormal megakaryocytes, as well as a few possible megakaryoblasts, but not all blasts were positive (Images 9, 10, 11 and 12).
Cytogenetic evaluation demonstrates one apparently normal cell line (46, XX), plus an abnormal clone with several cytogenetic abnormalities (Image 13):
The abnormalities include the following:
Additional chromatin material is seen attached to the long arms of chromosomes 21 and 22. A small marker chromosome of unknown origin is also present.