THELYMPHOMAS
The lymphomas are a group of malignant neo-. plasms that arise in lymph nodes or extranodal lymphoid tissue. They are a heterogeneous group of malignancies from both a pathological and a clinical viewpoint. The two major subgroups are Hodgkins’ disease and the non-Hodgkin’s lymphoma. In both these subgroups, the most common clinical presentation is that of a patient who notices an enlarged lymph node. Before the physician considers a biopsy of the enlarged node, he must obtain a thorough history and perform a physical examination and selected laboratory tests to evaluate possible causes of the swollen lymph node. Cervical lymphadenopathy most commonly is associated with infections such as streptococcal pharyngitis, infectious mononucleosis, and toxoplasmosis.
Axillary lymphadenopathy, particularly if it is unilateral, should direct the physician to perform a careful breast examination for possible cancer. Inguinal adenopathy may reflect skin infections of the legs or infection of the genitalia or anus such as syphilis. Scrofula,or tuberculous lymphadenitis, may present as asymptomatic isolated lymphadenopathy. Table 54-13 outlines various common causes’ of lymphadenopathy. If the cause of the enlarged lymph node(s) is not obvious after consideration of the above, the physician should consider lymph node biopsy for diagnosis.
Hodgkin’s disease is primarily a disease of young adults but also appears in children and the elderly. The patient usually presents with asymptomatic lymphadenopathy; for example, on a routine pre-employment chest x-ray the radiologist finds mediastinal lymphadenopathy. Some patients with Hodgkins’ disease have symptoms of fever, night sweats, or loss of weight; the factor or factors responsible for the production of these symptoms are not known.
Hodgkin’s disease is classified by pathological subtype, by clinical stage, and by the presence or absence of symptoms. The four pathological subtypes are nodular sclerosis, lymphocyte predominance, mixed cellularity, and lymphocyte depletion (Table 54-14). In all four subtypes the finding of Reed-Sternberg cells assures the pathologist that the diagnosis of Hodgkin’s disease is correct. The typical Reed-Sternberg cell is a large cell with two prominent nuclei. Each nucleus contains a prominent nucleolus surrounded by a “halo.” This pattern gives the cell the appearance of “owl’s eyes.” Pathologists have puzzled over the cell of origin of the Reed-Sternberg cell since it was first described around 1900. At present, the true macrophage or histiocyte rather than a lymphocyte is considered the progenitor of the Reed-Sternberg cell.