Primary Hematopoietic and Lymphoid Tissue ›› Bone Marrow ›› Abnormal

Increased B-Lymphoblasts






Microscopic Features:
  • 3-4x larger than a mature RBC
  • High nuclear to cytoplasmic ratio
  • Round Nucleus with immature chromatin (not clumped)
  • Prominent nucleoli
  • Cytoplasm is scant, light blue and lacks granules
Normal % blood-PB, marrow-BM, lymphoid tissue-LN:
  • PB: None
  • BM: None
  • LN: None
May Resemble:
  • Myeloblast
  • Pronormoblast
  • Immature B-cell (hematogone)
  • Monoblast
  • Prolymphocyte
  • Reactive lymphocyte
Differential Diagnoses:

If in blood or increased numbers in bone marrow:
B-Lymphoblastic leukemia/lymphoma (B-ALL)
CML lymphoblastic Bast crisis (usually it's myeloblasts but can sometimes be lymphoblasts)

Classic Immunophenotype:
  • CD19+
  • CD10+
  • CD20-
  • CD34+
  • TdT+
Cartoon Image:



Misc:
  • Blasts cells cannot be reliably distinguished from each other based on morphology alone. The exception are blasts with Auer Rod(s) which are unique to abnormal Myeloblast {16}s and abnormal promyelocytes as noted in some AMLs and APL Note: Abnormal B-lymphoblasts can show immunophenotypic abberancies (e.g. the gain of myeloid markers)