79 Hairy Cell Leukemia (HCL)
Michelle To and Valentin Villatoro
Two types of characteristic B lymphocyte morphologies can be seen in Hairy Cell Leukemia. Hairy cells are small to medium sized cells with either serrated cytoplasmic projections giving it a “hairy” appearance or more abundant pale blue cytoplasm giving it a “fried egg” appearance. The nucleus can be oval or indented, lacks nucleoli, and has an evenly stained mature chromatin patttern.
An indolent clonal mature B cell disorder has been associated with the BRAF -V600E mutation.
Age Group Affected:2,6
Middle-aged adults (median age of 55 years).
Laboratory Features for HCL:1,2,4,6
Peripheral Blood Smear:
Hairy Cells (± Fried egg appearance)
Dry Tap due to fibrosis (Aspirate)
CD19, CD20, CD22, CD25, CD123, Annexin A1
Other useful tests:
Tartrate-resistant acid phosphatase (TRAP) stain positive
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