Adult T-Cell Leukemia/Lymphoma (ATCL)

Definition

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.

Sample Cases

Click here for instructions on how to download the free FCS Express Reader to view and manipulate the sample cases.

Epidemiology

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.

Possible causes

The cause is unknown.

Morphology

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.

Immunophenotyping

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 dot plot.

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. Munerous chromosome abnormalities are usually seen.                        

Sub-classification

There are two variants seen based on morphologic features: T-zone variant and the Lymphoepithelioid cell variant.

Flow Diagnosis

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.                        

References

Contributors to this page