The lymphoma cell is a peripheral T lymphocyte in various stages of differentiation. The neoplastic clone expresses T-cell antigens and is usually CD4+. The malignant T-cells are believed to secrete cytokines responsible for the polyclonal B-cell hyperplasia observed in involved nodes. Clonality studies demonstrated a monoclonal rearrangement of the b-chain of the T-cell receptor (TCR) in the majority of cases. In some cases clonality could not be demonstrated. This led some authors to postulate the existence of at least two types of AILD, namely a reactive and benign type and a lymphomatous form.

The disease is rare

The disease preferentially affects elderly males (male-to-female ratio 3:1, median age around 60 years). Most patients present with generalized lymphadenopathy, hepatosplenomegaly, skin rash and general symptoms (fever, weight loss). Polyclonal hypergammaglobulinemia is a common finding.

The lymph node architecture is effaced and no reactive germinal centres are usually observed. The infiltrate may involve the perinodal fat. There is a proliferation of high endothelial venules with clusters of follicular dendritic cells. The lymphoid infiltrate consists of small-to-large cells resembling immunoblasts and atypical clear cells with round nucleus and abundant pale cytoplasm. The latter cells may occur in small aggregates or sheets.

Some patients respond to steroids; in steroid-unresponsive patients multiagent chemotherapy usually produces short lasting responses.

Few patients present spontaneous or steroid-induced remission; the majority of cases feature an aggressive disease with short survival despite chemotherapy. Most patients die with infection and active disease.

Median survival is about 1-3 years.

A mixture of normal and abnormal cells is usually seen in the vast majority of cases. The cytogenetic picture at disease presentation may be normal in some cases which may develop clonal abnormalites during the course of the disease. The following karyotype pattern can be found

Using probes for the detection of +3, +5 and +X, the vast majority of cases can be shown to carry aneuploidy.