High grade B cell non-Hodgkin's lymphoma (NHL) is an increasingly important problem in individuals infected with the human immunodeficiency virus (HIV). Fifty percent of these tumours harbour the Epstein-Barr virus (EBV) and there is an equal frequency of EBV A and B-subtypes in the tumours. This contrasts with the recent report that only A-type EBV is associated with Hodgkin's disease. Such studies are challenging the traditional models of EBV-associated lymphomagenesis and showing the way for further studies in this field. This article reviews the studies of EBV subtypes in HIV-associated NHL and uses this new knowledge to discuss the role of EBV in lymphomagenesis.

Clinicians should be aware of malignant transformation within a plaque of necrobiosis lipoidica. Early detection will allow conservative treatment.

An unusual primary intestinal lymphoma that occurred as a complication of ileal Crohn's disease is presented. Immunohistochemistry confirmed the light microscopic diagnosis of Hodgkin's disease (nodular sclerosing), and characterized a distinct mucosal nodule as a large‐cell anaplastic non‐Hodgkin's lymphoma. This unusual lymphoma developed while the patient was being treated with immunosuppressant medication. The present report is a reminder to clinicians of the possibility of occult lymphoma in ileal Crohn's disease.

Epstein-Barr virus (EBV) has been associated with Hodgkin‧s disease (HD) in up to 50% of cases, but the subtype of EBV involved has only recently been studied. In this report, biopsy samples from 30 patients with HD were assessed for EBV sequences using both the polymerase chain reaction (PCR) and in situ hybridization (ISH). EBV sequences were localized to the malignant Reed-Sternberg cells and their mononuclear variants (Hodgkin's cells) in 9 of the 30 cases, with 7 demonstrating A- type and 2 B-type EBV sequences. Both of the patients with B-type EBV- associated HD had features to suggest pre-existing immune compromise: one was infected with human immunodeficiency virus (HIV) and had severe CD4+ T-lymphocyte depletion; the other was a debilitated elderly patient with dementia. A previous study suggested that A-type EBV alone is associated with HD and the finding of predominantly A-type EBV in the present series is in keeping with this report. The presence of B- type EBV in the HD of patients with pre-existing immunodeficiency, taken together with the recent report that B-type EBV occurs in HIV- associated non-Hodgkin‧s lymphoma, suggests that B-type EBV may be an important human pathogen in immunocompromised patients.

SUMMARY Polyclonal B cell activation is characteristic of HIV infection and occurs in the presence of severe CD4+ lymphocyte depletion. In contrast, CD4+ lymphocytes are the dominant T cell in the reactive lymphoid tissues of patients not infected with HIV. In this study, lymph node biopsies from eight HIV‐infectcd patients with persistent generalized lymphadenopathy syndrome (PGL) were assessed for IL‐lβ, IL‐2, IL‐4, IL‐6, IL‐10, interferon‐gamma (IFN‐γ) and tumour necrosis factor‐beta (TNF‐β) gene expression using the polymerase chain reaction (PCR). The cytokine gene expression of two cases of reactive adenopathy in patients not infected with HIV was assessed for comparison. IFN‐γ was expressed much more strongly in the PGL samples than in control reactive lymphoid tissues, whereas the other cytokines were expressed to a similar extent in both types of tissues. IFN‐γ may have an important role in maintaining the adenopalhy of HIV‐infected patients. Expression of cytokines such as IL‐2, IL‐4 and IL‐10 in HIV nodes may be adequate to allow the recruitment of naive B cells to the reactive process.