Splenic B-cell Leukemia, Hairy Cell Leukemia Variant
Kathryn Foucar, MD
Key Facts
Terminology
Mature monoclonal B-cell neoplasm with hybrid features
Leukocytosis with normal monocyte count
Hairy projections and nucleoli
Absence of some classic HCL antigens (CD25, annexin-A1, CD123)
Red pulp infiltration of spleen
Etiology/Pathogenesis
Derived from post-germinal center activated B cell
Currently thought to be unrelated to classic HCL
Clinical Issues
Lack response to typical agents used in HCL
Microscopic Pathology
Typically aspirable (no fibrosis)
Subset of cases show predominant sinusoidal pattern
 Blood from an 81-year-old patient with HCLv shows prominent lymphocytosis with partial hairy projections and central nucleoli with preserved hemoglobin levels and platelet count. |
 High magnification of HCLv cell shows prominent nucleolus and partial hairy projections in an 88-year-old woman with anemia, thrombocytopenia, and a normal absolute monocyte count. |
TERMINOLOGY
Abbreviations
Splenic B-cell leukemia, unclassifiable (SBCL-U)
Hairy cell leukemia variant (HCLv)
Definitions
Mature monoclonal B-cell neoplasm with hybrid features
Leukocytosis with normal monocyte count
Hairy projections and nucleoli
Absence of some classic HCL antigens (CD25, annexin-A1, CD123)
Red pulp infiltration of spleen
ETIOLOGY/PATHOGENESIS
HCLv
Pathogenesis unknown; likely unrelated to classic HCL
Derived from post-germinal center activated B cell
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