Hairy cell leukemia (HCL) is characterized by tartrate-resistant acid phosphatase (TRAP) positivity and strong expression of which surface marker that also serves as a target for the monoclonal antibody rituximab?
- A CD20 ✓
- B CD19
- C CD22
- D CD25
Correct answer: A. CD20
Explanation
Hairy cell leukemia is a mature B-cell neoplasm with the immunophenotype CD19+, CD20+, CD22+, CD25+, CD11c+, CD103+, annexin A1+. CD20 is the target of rituximab (anti-CD20 antibody), and rituximab is used in combination with cladribine (purine analog) or as single-agent therapy for HCL. The BRAF V600E mutation is present in nearly all HCL cases and is pathognomonic. TRAP positivity on cytochemistry and the hair-like cytoplasmic projections on peripheral smear are classical morphological features.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.