Diffuse large B-cell lymphoma with expression of full-length ALK

Definition

A large cell lymphoma resembling anaplastic large cell lymphoma but lacking immunoreactivity for CD30, lacking T- and B-cell lineage markers, but probably of B-cell lineage based on clonal immunoglobulin gene rearrangement.

Clinical features

Patient are usually adult, with a male predominance1. Usually presents with lymphadenopathy and often at an advanced stage1. Splenomegaly is not common1.

Histopathology

Resembles anaplastic large cell lymphoma. This variant is composed of monomorphic large immunoblast-like cells, sometimes with plasmablastic differentiation. Binucleate Reed-Sternberg-like are a feature. In some cases, malignant giant cells may be seen1.  There is a prominent patterns of sinusoidal infiltration: some nodes which are otherwise uninvolved may show sinusoidal infiltration1. Plasma cells may be numerous but cells intermediate between the malignant cells and the plasma cells are not seen1.

Immunohistochemistry

Other T and B cell markers are negative.

Genetics

Lacks t(2:5) translocation and the NPM-ALK fusion protein is not demonstrable1. There is clonal rearrangements of the immunoglobulin heavy chain gene1.

Molecular studies

Show expression of the full length of the ALK gene product1.

Prognosis

The course is usually aggressive1.

 References

World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

1 Delsol G, Lamant L, Mariame B et al.  A new subtype of large B-cell lymphoma expressing the ALK kinase and lacking the 2;5 translocation.   Blood 1997;89:1483-90. FULL TEXT

4 Adv Anat Pathol 1997;5:333.

5 Christie Problems in Tumour Pathology, 7.6.2002