1. Early T-Cell Precursor ALL in 5 Year Old Female
Bryan Danilchuk, BS, MLS (ASCP)CM
Boston Children’s Hospital Department of Laboratory Medicine
ABSTRACT
PERIPHERAL BLOOD IMMUNOPHENOTYPE
BONE MARROW IMMUNOPHENOTYPE
 A 5-year-old female presented with severe fatigue and fevers of two week duration and a large, painful skin lesion on the left calf. Upon initial laboratory exam, it was noted she was extremely pancytopenic with a peripheral blood differential revealing the presence of 8% blast cells. Peripheral blood immunophenotyping discovered the presence of both lymphoid and myeloid markers present on the blasts. A bone marrow aspirate and biopsy were performed and demonstrated 70% cellularity, composed of 90% lymphoblasts. The lymphoblasts expressed an immunophenotype of CD34, CD71, and CD11b. The majority of the cells also co-expressed CD7, CD13, CD33, CD56, CD123, and cytoplasmic CD3. The blasts did not express surface CD1a, CD3, CD4, CD5, CD8, CD10, CD16, CD19, or CD20. They were also negative for myeloperoxidase, while expressing TdT. An immunophenotype with the absence of CD1a, CD8, and weak CD5, while expressing at least one of the following myeloid markers: CD13, CD11b, CD33, CD34, CD56, CD117, or HLA-DR, correlates with an extremely poor prognosis of early T-cell precursor ALL. The patient was started on an intensive chemotherapy regime and entered a continued remission after day 32 of induction.
PERIPHERAL BLOOD IMMUNOPHENOTYPE
INTRACELLULAR STAINING FOR CYTOPLASMIC CD3
The patient’s peripheral blood blast immunophenotype was positive for some myeloid (CD11b and CD33) and immature T-lymphoid (CD7 and CD2 variable) markers. A bone marrow biopsy and aspirate were performed in addition to intracellular marker staining for cytoplasmic CD3 to help finalize the diagnosis.
PATIENT OUTLOOK
The immunophenotype of the patient’s blast cells were positive for both myeloid and lymphoid markers in addition to precursor hematopoietic stem cell marker, CD34. While negative for surface CD3, intracellular staining was positive for cytoplasmic CD3, and negative for intracellular IgG isotype (negative control). This indicates that the blasts are very immature T-cells. Early T cell precursor (ETP) T-ALL accounts for a fifth of all childhood T-ALL cases. An immunophenotype which is CD1a-, CD8- and CD5 (weak to negative) accompanied by the presence of myeloid markers indicate a very poor prognosis with the use of standard intensive chemotherapy.2 In a study at St. Jude’s Hospital, patients with ETP T-ALL over a 10 year period have a relapse rate of 72% vs a 10% relapse rate with typical T-ALL.2 This patient has been on an intensive chemotherapy regime since presentation and has been in remission since day 32 of induction.
BONE MARROW IMMUNOPHENOTYPE
REFERENCES
1.Carey, J. L., McCoy, J. P., & Keren, D. F. (2007). Flow Cytometric Analysis of Acute
Leukemias, Myelodysplastic Syndromes, and Myeloproliferative Disorders. Flow
cytometry in clinical diagnosis (4th ed.). Chicago, IL: American Society for Clinical
Pathology.
2.Coustan-Smith, E., Mulligan, C. G., Onciu, . M., Behm, P. F., Raimondi, P. S., Pei, D., et
al. Early T-cell precursor leukaemia: a subtype of very high-risk acute lymphoblastic
leukaemia. The Lancet Oncology, 10, Retrieved May 29, 2014, from the
Pubmed.gov database.
Upon presentation, her peripheral blood had a WBC count of 0.77 x109/L, RBC count of 1.55 x1012/L, hemoglobin/hematocrit of 45 g/L and .128 L/L, respectively, and platelet of 19 x109/L indicating pancytopenia. Acute lymphoblastic leukemia (ALL) is the most common leukemia among children and 85% of ALL cases are precursor B-cells.1 With this notion in mind, B-cell precursor markers were tested first. Initial immunophenotyping of the peripheral blood revealed a population of blast cells that were CD34+ but CD19-, CD20-, and CD10-. This immunophenotype does not correlate with precursor B-ALL therefore more cell markers were tested.
CONTACT INFORMATION
Bryan Danilchuk, BS, MLS (ASCP)CM,