
Anaplastic Large Cell Lymphoma (ALCL)
- This is a T-cell lymphoma composed of large cells. The majority of patients present with Stage III or IV disease with peripheral and/or abdominal lymphadenopathy. Extra-nodal infiltration is common including the bone marrow. It mainly affects children and young adults.
- Tumour cells of ALCL are positive for the anaplastic lymphoma kinase (ALK) protein. A minority of ALCL cases are ALK negative. These carry a poorer outlook and probably are a separate entity.
- Immunophenotypically, ALCL is ALK positive with cytoplasmic and nuclear staining. CD30+ cell membrane and golgi, EMA positive and one or more T-cell antigens, CD2 and CD4 most commonly, are positive. CD3 is positive in only 25% of cases.
- Cytogenetics and molecular biology. 95% of ALCL show clonal rearrangement of the T-cell receptor gene. Expression of ALK in ALCL is due to genetic changes at the ALK locus on chromosome 2. t(2;5) is the commonest cytogenetic change.
Management
Response to chemotherapy such as CHOP in the ALK+ group is good and up to 70% appear to be cured by this treatment even with advanced disease. In ALK-negative patients the outlook is extremely poor with only 15-30% long term survivors. See Savage KJ, Blood Reviews (2007); 21:201-16 for a review of T cell lymphoma.
Topic Code: 5961