Angioimmunoblastic T Cell Lymphoma
Supplemental Studies
Immunohistology and Flow Cytometry
- Neoplastic T cell population:
- T lineage markers
- CD2+
- CD3+
- CD4 ~90% +
- CD5+
- CD7 often lost (~1/3+)
- Germinal center T cell markers
- CD10 60-90%+
- Native germinal center B cells are larger and weakly CD10+
- Granulocytes are strongly CD10+
- CXCL13+
- Bcl6 70-80%+
- Proliferation of follicular dendritic cells outside follicle centers/around high endothelial venules is characteristic
- CD21+ (more sensitive marker)
- CD23+
Genetic analysis
- Molecular clonality studies
- 80-90% of cases show clonal T cell receptor gene rearrangement
- ~1/4 of T cell gene rearrangements are oligoclonal
- ~ 1/3 show immunoglobulin gene rearrangement
- rare cases show immunoglobulin gene rearrangement in the absence of a T cell receptor gene rearrangement
- Cytogenetic abnormalities often present
- help establish clonality
- not specific for this diagnosis
- In situ hybridization for EBV early region RNA (EBER):
- ~50% of cases positive, including 70% of cases with accompanying B cell proliferation
- EBV+ cells correspond to CD20+ B immunoblasts
Clinical laboratory
- A variety of abnormalities may be found
- Cold agglutinins
- Positive Coombs test
- Circulating immune complexes
- Anti-smooth muscle antibodies
- Rheumatoid factor
- Anti-nuclear antibodies
- Paraproteins
- Cryoglobulins
