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

Increased B-Lymphoblasts


Click Here for Full Size

---

› 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 [Compare]
• Pronormoblast [Compare]
• Immature B-cell (hematogone) [Compare]
• Monoblast [Compare]
• Prolymphocyte
• Reactive lymphocyte [Compare]

› 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:


Click and drag

for direct comparison
› 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)