Non-Hodgkin’s Lymphoma

Epidemiology

There are two basic categories of lymphoma: Hodgkin’s disease (HD) and non-Hodgkin’s lymphoma (NHL). Together they account for approximately 3 to 5% of all newly diagnosed malignancies and deaths in developed countries. NHL is more common than HD and represents 60 to 70% of all lymphomas. These tumors affect all age groups. The distribution is, however, bimodal with a peak in young adulthood followed by a plateau in middle age and a steep rise in old age.

Clinical Findings

NHL can present either with lymph node enlargement, an extranodal mass, or both. Patients with masticator space NHL may have trismus or pain that may be associated with or without cervical lymphadenopathy. The incidence of systemic signs such as fever is 10 to 15%.

Pathology

Histologic classification of NHL is notoriously difficult but newer techniques for classification such as immunologic phenotyping, nucleic acid analysis with flow cytometry, and molecular genetics may help to explain the apparent diversity of morphological appearances. One of the most popular classifications is the Rappaport system, which is based on pattern of involvement and cellular appearance. In general, nodular lymphomas have a more indolent course compared with the diffuse variety. HD is almost always confined to lymph nodes, whereas 40 to 60% of NHL present have extranodal involvement. Approximately, one third to two thirds of extranodal involvement is found in the head and neck. The most common head and neck sites are the orbits and Waldeyer’s ring. Masticator space NHL is rare.