Hairy cell leukaemia

Definition

A neoplasm of small B lymphoid cells with oval nuclei and abundant cytoplasm with "hairy" projections, which diffusely infiltrates bone marrow and splenic red pulp and strongly expresses CD11c, CD22 and CD103.

Synonyms

Epidemiology

A rare disease, constituting 2% of lymphoid leukaemias. Patients are middle-aged to elderly.

Clinical features

Bone marrow and splenic involvement predominate, most patients presenting with splenomegaly and pancytopenia. There may also be infiltration of lymph nodes and live, occasionally of skin. Rarely there is marked abdominal lymphadenopathy due to infiltration by large hairy cells. Recurrent opportunistic infections, vasculitis and immune dysfunction are common.

Histopathology

Hairy cells are small to medium in size, with reniform nuclei. There is abundant pale blue cytoplasm. Occasionally the cytoplasm is vacuolated or contains rod-shaped inclusions. There is strong tartrate-resistant acid phosphatase (TRAP) positivity. Bone marrow involvement is by widely spaced nuclei surrounded by abundant cytoplasm with prominent cell borders, giving a "fried egg" appearance. Reticulin is increased and may result in a "dry tap" on aspiration. In some cases, the marrow is hypocellular, resembling an aplastic anaemia: a B cell marker will demonstrate the neoplastic infiltrate.

Splenic involvement is localised to the red pulp, with atrophy of the white pulp. Red blood cell lakes occur. The liver may show infiltration of sinusoids. Lymph node infiltration is predominantly paracortical.

Immunohistochemistry

CD5

negative

 

CD10

negative

CD11c†

positive (strong)

CD19†

positive

CD20

positive

CD22

positive

CD23†

negative

CD25

positive (strong)

CD68

positive

CD79a

positive

CD79b

negative

CD103

positive

SIg

+ (M+/D-, G or A)

FMC7

positive

DBA.44

positive

TIA-1

5/93

 

granzyme-B

0/93

 

perforin

0/93

 

CD11c (LeuM5)

8/93

 

CD25 (IL-2R)

7/93

 

FMC7

6/93

 
     

†: fresh frozen tissue only

Almost all cases are positive for tartrate-resistant acid phosphatase (TRAP), as are some other low-grade B cell lymphoproliferative disorders. DBA44 is very sensitive for hairy cell leukaemia but may be positive in other B cell lymphoproliferative disorders. CD68 coexpression is unusual in other B cell lymphoproliferative disorders.

Variant

Differential diagnosis

Prognosis

Prolonged remission may follow splenectomy. HCL-V has a poor response to treatment and a shorter survival.

References

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

Wotherspoon AC, Hasserjian RP. Immunophenotyping in the differential diagnosis of histologically low grade B cell lymphomas. Current Diagnostic Pathology 2000;6:55-63.

1EJ Schlette. B-cell prolymphocytic leukaemia. Pathology Case Reviews 2000;5 (5):274-280.

2Nazeer, T., Burkart, P., Dunn, H., Jennings, T.A. and Wolf, B. Blastic transformation of hairy cell leukemia. Arch Pathol Lab Med 1997;121:707-13.

3Mori, N., Y. I. Murakami, et al. (2004). "TIA-1 expression in hairy cell leukemia." Mod Pathol 17(7): 840-6.

 

This page last revised 1.9.2004.

©SMUHT/PW Bishop