• All IHC stains will include a positive control tissue

• Annexin A1 is used to differentiate hairy cell leukemia from other B-cell lymphomas including hairy cell leukemia variant. In the differential diagnosis of hairy cell leukemia and other B-cell neoplasms, Annexin A1 has a sensitivity of 96% and specificity of 100%. Consider using Annexin A1 as part of a panel of testing (BRAF, TRAP).
• Annexin A1 is positive in normal T-cells and myeloid cells. Positivity has also been reported in T-cell leukemias/lymphomas, AML, CMML, CML, P. vera, ET, primary myelofibrosis, mast cell disease, carcinomas, and some sarcomas.

Submit a formalin-fixed, paraffin embedded tissue block

Formalin-fixed, paraffin embedded (FFPE) tissue block

Tissue section mounted on a charged, unstained slide

Ambient (preferred)

• Unlabeled/mislabeled
• Insufficient tissue
• Slides broken beyond repair

Immunohistochemical staining and microscopic examination

If requested, an interpretive report will be provided

Specifications

Annexin A1 is a protein encoded by the ANXA1 gene. The protein has multiple functions and is upregulated in hairy cell leukemia.
 
Staining pattern

Membranous and cytoplasmic



References

1. Sherman MJ, Hanson CA, Hoyer JD. An Assessment of the usefulness of immunohistochemical stains in the diagnosis of hairy cell leukemia. Hematopathology 2011;136:390-399.
2. Wang HY, Zu Y. Diagnostic algorithm of common mature B-cell lymphomas by immunohistochemistry Arch Pathol Lab Med 2017;14:1236-1246.