High Specificity of Combined TRAP and DBA.44 Expression for Hairy Cell Leukemia

Abstract

Because of marrow fibrosis, bone marrow aspirations are often nonconclusive in patients with hairy cell leukemia (HCL). Therefore, histologic examination is important in HCL but often difficult in cases with low numbers of tumor cells. A combined immunohistochemical positivity for DBA.44 and tartrate-resistant phosphatase was previously found in 100% of HCL and suggested to be specific for this diagnosis. To further assess the diagnostic specificity and sensitivity of this immunohistochemical approach in a higher number of cases, we analyzed 56 HCLs and lymphoma tissue microarrays, including 840 cases of the most frequent non-Hodgkin lymphomas. All HCLs showed combined positivity for these two proteins (100% sensitivity). Both antibodies were often positive in other lymphoma types. DBA.44 reactivity was especially frequent in follicular lymphomas (46%), whereas tartrate-resistant acid phosphatase (TRAP) expression was often seen in mantle cell lymphomas (57%), primary mediastinal large B-cell lymphomas (54%), and chronic lymphocytic leukemia/small lymphocytic lymphoma (41%). A combined DBA.44/TRAP positivity was seen in only 3% of non-HCL non-Hodgkin lymphomas, including cases of diffuse large B-cell lymphomas, follicular lymphomas, chronic lymphatic leukemia/small lymphocytic leukemias, and mantle cell lymphomas. Overall, these data confirm the utility of combined immunohistochemical DBA.44/TRAP expression analysis in confirming the diagnosis of HCL. However, combined positivity for these markers is highly sensitive but not absolutely specific for HCL.

Immunohistochemistry in bone marrow pathology: a useful adjunct for morphologic diagnosis

“…Like T-LGL, HSTCL shows an intrasinusoidal and subtle interstitial infiltration pattern, which is difficult to recognize by morphology alone. HSTCL is usually positive for CD3 and TIA-1 and frequently expresses CD56, whereas CD4, CD8, granzyme B, and perforin are negative [15,36,162].…”

T-bet Transcription Factor Detection Facilitates the Diagnosis of Minimal Hairy Cell Leukemia Infiltrates in Bone Marrow Trephines

“…To establish the diagnosis of HCL in this difficult diagnostic setting, the antigens DBA.44 11 and tartrate-resistant acid phosphatase (TRAP) 1 have been found to be useful particularly when used in combination. 16 This does, however, not always solve the diagnostic dilemma as DBA.44/TRAP double positivity is not absolutely specific for HCL. Also the demonstration of CD25 13 in paraffin sections is of limited specificity.…”

Bone Marrow

“…43-25D), 368 and the combined expression of TRAP and DBA.44 is reported to be fairly specific for HCL. 369 Cytogenetic studies are usually not helpful because of limited growth of the specimens. Although no specific abnormality has been described for HCL, clonal abnormalities involving chromosome 5, including trisomy 5, are reported in 40% of cases.…”