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

Clinical features

Usually presents with lymphadenopathy and often at an advanced stage.

Histopathology

Resembles anaplastic large cell lymphoma. This variant is composed of monomorphic large immunoblast-like cells, sometimes with plasmablastic differentiation. Reed-Sternberg-like cells may be seen.  There is a prominent patterns of sinusoidal infiltration.

Immunohistochemistry

CD4	may be positive
CD19	negative
CD20	negative
CD22	negative
CD30	negative
CD45	variable, weakly positive
CD57	may be positive
CD79a	negative
ALK1	positive (mainly in a granular pattern in the cytoplasm and Golgi)
ALK-EC	positive (in a cell membrane pattern)
EMA	strongly positive
VS38	positive
cytoplasmic IgA	often positive with light chain restriction1

Other T and B cell markers are negative.

Genetics

Lacks t(2:5) translocation and the NPM-ALK fusion protein is not demonstrable.

Shows clonal rearrangements of the immunoglobulin heavy chain gene.

Prognosis

The course is aggressive.

 References

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

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.

Adv Anat Pathol 1997;5:333.

¹Christie Problems in Tumour Patholgy, 7.6.2002