Primary Systemic Anaplastic Large Cell Lymphoma
Supplemental Studies
Immunohistochemistry and flow cytometry
- Non-lineage specific markers
- ALK1
- 60-85% of cases overall
- 91% of pediatric cases positive
- CD30 >95%
- In small cell and lymphohistiocytic variants, strongest CD30 staining is present in larger cells in perivascular location
- EMA >95%
- Keratin reported in some older studies
- clusterin > 90%
- CD45 >90%
- CD56 (NCAM) 15%
- T lineage-associated markers
- T cell antigen loss is common, but most cases express at least one
- Rare cases with “null-cell” phenotype by immunohistochemistry
- CD43, CD45RO commonly positive (~2/3 positive)
- CD43 is also expressed in monocytes, acute myeloid leukemia, and some B cell lymphomas
- CD2, CD4, LAT sometimes positive (40-50%)
- LAT is also expressed in megakaryocytes, mast cells
- CD3, CD5, CD7, CD8 commonly negative (<25% positive)
- Cytotoxic proteins
- TIA-1, granzyme B, or perforin (80-90% positive)
- > 90% positive for one or more
Genetic analysis
- Gene translocation involving ALK is definitional if present and correlates with ALK1 expression pattern by immunohistochemistry
- t(2;5) translocation (ALK-nucleophosmin)
- most common (70-80 %)
- cytoplasmic and nuclear ALK1 by immunohistochemistry
- t(1;2) translocation (tropomyosin3-ALK)
- 10-20%
- cytoplasmic ALK1 by immunohistochemistry
- a variety of other less common translocations involving ALK predominantly show cytoplasmic ALK1 by immunohistochemistry
- Most cases show T cell receptor gene rearrangements (but are negative for immunoglobulin gene rearrangements)
- May be useful in cases with a “null-cell” phenotype by immunohistochemistry
