B-cell prolymphocytic leukaemia

Definition

A neoplasm of B-prolymphocytes affecting blood, bone marrow and spleen. Prolymphocytes must exceed 55% of lymphoid cells in the blood. Cases of transformed CLL with increased prolymphocytes are excluded. De novo B-cell prolymphocytic leukaemia is uncommon1.

Synonyms

Epidemiology

This is a very rare condition, constituting 1% of lymphocytic leukaemias. Most patients are over 60 years of age.

Clinical features

There is involvement of peripheral blood, bone marrow and spleen. Patients have marked splenomegaly without lymphadenopathy. The white cell count usually exceeds 100.109/l. 50% of patients show anaemia and thrombocytopenia.

Histopathology

Most circulating cells are prolymphocytes. Similar cells are seen as a diffuse intertrabecular infiltrate in the bone marrow. The spleen shows involvement of both red and white pulp. Lymph nodes show a diffuse or vaguely nodular infiltrate of similar cells without pseudofollicles.

Immunohistochemistry

CD5	one third of cases
CD19	positive
CD20	positive
CD22	positive
CD23	usually negative
CD79a	positive
CD79b	positive
FMC7	positive

: fresh frozen tissue only

Cytogenetics

Abnormalities of chromosome 7 have been reported1.

Differential diagnosis

Transformed CLL with increased prolymphocytes.
Cases with t(11;14) may be better classified as leukaemic mantle cell lymphoma1.

Prognosis

Survival is usually short

References

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

1 Schlette E, Bueso-Ramos C, Giles F, et al. Mature B-cell leukemias with more than 55% prolymphocytes. A heterogeneous group that includes an unusual variant of mantle cell lymphoma. Am J Clin Pathol 2001; 115:571-81

This page last revised 17.11.2006.