Non-Hodgkin's lymphoma

Non-Hodgkin's lymphoma (NHL) is a type of lymphoma - a tumour that involves the uncontrolled multiplication of a type of white blood cell called lymphocytes. NHL may occur either in the lymph nodes or elsewhere, such as the spinal cord and brain (the central nervous system [CNS]), the gastrointestinal tract, the liver or kidneys. It has also occurred in unusual sites such as the anus, rectum, mouth, muscle and other soft tissue.

NHL, also known as B-cell lymphoma, is the most common lymphoma seen in people with HIV, and is diagnostic of AIDS. There are several types of AIDS-associated lymphomas:

  • Small non-cleaved cell or Burkitt's lymphoma.
  • Diffuse large cell lymphomas: large non-cleaved cell lymphomas, immunoblastic plasmacytoid lymphomas, and primary central nervous system lymphomas.
  • Primary effusion lymphomas.

The other main kind of lymphoma is Hodgkin's disease - see Hodgkin's disease in A to Z of illnesses.

When NHL first occurs in the CNS it is known as primary CNS lymphoma. This can occur at a wide range of CD4 counts: 75% of people with primary CNS lymphoma have a count above 50 cells/mm3, although most have a CD4 count below 200 cells/mm3. If the lymphoma occurs outside the CNS it is called systemic lymphoma. Seventy-five percent of cases occur in people who have already experienced multiple opportunistic infections. Longer duration of HIV infection is associated with greater risk of lymphoma, independent of CD4 cell count.

NHL among people with HIV is more aggressive, and responds less well to therapy, than in HIV-negative people. NHL has been associated with a poor prognosis in people with HIV although survival time has been extended since the introduction of highly active antiretroviral therapy (HAART). In the past, people with AIDS-related NHL lived for an average of four to eleven months after their NHL diagnosis, depending on the severity of immune suppression, while those with primary CNS lymphoma lived for an average of two to four months, regardless of CD4 cell count. However, recent research has shown that people with NHL who were treated with HAART had a median survival time of two years.1

References

  1. Thirlwell C et al. Acquired immunodeficiency syndrome-related lymphoma in the era of highly active antiretroviral therapy. Clin Lymphoma 2003; 4: 86–92, 2003