Adult T cell lymphoma / leukaemia, ATLL

Definition

A peripheral T-cell neoplasm caused by the human T-cell leukaemia retrovirus, type 1. (HTLV-1).

Synonyms

Epidemiology

 ATLL is endemic in Japan, the Caribbean and Central Africa. Sporadic cases of ATLL occur elsewhere. The median of onset of ATLL is 55 years.

Clinical features

 Patients present with generalised lymphadenopathy. The skin is most commonly involved, followed by lung, liver, gastrointestinal tract and CNS.

Clinical variants:

• acute ATLL manifests as a markedly raised WBC with eosinophilia, skin rash, generalised lymphadenopathy, hepatosplenomegaly and hypercalcaemia, with or without lytic bone lesions. Opportunistic infections with Pneumocystis carinii and Strongyloides are common.

• lymphomatous ATLL is characterised by generalised lymphadenopathy without leukaemia.

• chronic ATLL is associated with an exfoliating skin rash and limited numbers of atypical circulating white cells

• smoldering ATLL shows a normal WBC with <5% circulating neoplastic cells, cutaneous and pulmonary lesions. There is usually a long latent period before progression to an acute form.

Histopathology

 The acute and lymphomatous variants show pleomorphic medium to large lymphoid cells with distinct nucleoli. The nuclei may be polylobated ("flower cells"). Marrow infiltration is patchy. The skin shows dermal infiltration with Pautrier-like microabscesses. Lymph nodes may show sinuses dilated with neoplastic cells; there may be an eosinophilia.

• The chronic and smoldering variants have smaller neoplastic cells with minimal pleomorphism. The skin shows a sparse dermal infiltrate with hyperkeratosis. In some cases, he lymph nodes closely mimic Hodgkin lymphoma with paracortical infiltration by small lymphocytes an Reed-Sternberg-like cells. The RS-like cells are EBV-positive and express CD15 and CD30. These cases usually show rapid progression.

Immunohistochemistry

CD2	positive
CD3	positive
CD4	usually positive
CD5	positive
CD7	negative
CD8	usually negative, rarely CD4-/CD8+ or CD4+/CD8+
CD15	RS-like cells in lymph nodes may be positive
CD25	almost always positive
CD30	large transformed cells may be positive
TIA-1	negative
granzyme B	negative
ALK	negative

†: fresh frozen tissue only

References

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

This page last revised 20.12.2002.

©SMUHT/PW Bishop