Adult T-Cell Leukemia/Lymphoma (ATCL)
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Adult T cell leukemia/lymphoma (ATCL) is a T cell lymphoma with leukemic manifestations involving lymph nodes, skin, spleen and liver. The neoplastic circulating cells vary in size, but characteristically are large multilobulated lymphoid cells. They are T cells, nearly always T helper cells (CD 4 positive) and show aberrant expression of T cell antigens.
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|case 15||Mature T cell lymphoid leukemia
This case was kindly provided by the ASCP Press. It is part of Flow Cytometry in Clinical Diagnosis by John Carey, Phil McCoy and David Keren.
HTLV1 is strongly associated with ATCL. ATCL is localized to the Caribbean, southeastern US, and most notably southern Japan. The prognosis is poor with most patients dying within 1-2 years.
The cause is unknown.
These cells are predominantly medium to large cells with irregular, pleomorphic nuclei with prominent nucleoli. Mitotic figures may be present.
|Example morphology of ATCL cells.||Example morphology of ATCL cells.|
The CD45 vs SSC gating dot plot identifies a population of large cells (green population) and small lymphocytes (red population). The ATCL will fall in the larger cell region as they have bright CD45 and moderate to high SSC.
| Example case of ATCL CD45 vs SSC gating
Aberrant expression of T cell antigens in ATCL with CD3 positive and CD7 negative antigen expression (CD3 +; CD7 + expected on normal T cells). The ATCL cells express CD 25 (the interleukin 2 receptor).
Below are selected example dual paramenter dot plots of a case of ATCL:
|The pan T cell markers are generally expressed; however, aberrant marking of one or more is common. Loss of CD7 is the most common aberrancy.||These large cells express CD4 , CD8 is not expressed.||This cell type is proliferative and agressive as seen by the aneuploidy and high SPF. Some cases of ACTL also express CD30.|
Other relevant tests
Genetics: TCR genes are clonally rearranged in most cases. Numerous chromosome abnormalities are usually seen.
There are two variants seen based on morphologic features: T-zone variant and the Lymphoepithelioid cell variant.
Flow cytometry immunophenotyping shows large cells CD45 bright and SSC moderate to high. The pan T cell markers are expressed, but aberrant phenotypes are common. CD4 is usually expressed and not CD8. CD30 and CD25 can be expressed in some cases.