Non-Hodgkin's Lymphoma

Risk: Risk factors for NHL include occupational risks such as anesthesiology, carpentry, chemical industries, construction, engineering, farming, fishing, forestry, leather work, mechanics, metal working, road transport industry, rubber industry, sales and clerical work, and certain food industry occupation. Most of these associations are weak or inconsistent; further studies are underway to confirm these findings. Other risk factors may include exposure to vinyl chloride, pesticides, and hair dyes, as well as ingestion of certain prescription medications.

Incidence and Prevalence: The worldwide incidence of NHL ranges from 3.7 to 14.0 per 100,000 individuals, higher in more developed countries. The US incidence rate for NHL is 16 per 100,000 people for both men and women combined; the rate of development of new cases has been increasing since the 1970s, e.g., from 45,000 new cases in 1994 to 56,200 reported in 2001 (Nayak). The increasing incidence is generally attributed to the increase in HIV cases; NHL occurs in 15% of AIDS cases (Nayak). Generally NHL occurs in individuals older than 24 years of age, although the incidence increases with age, peaking after age 60.

History: Individuals usually report a painless or slightly tender, swollen lymph node in the neck, underarm, or inner thigh (ilioinguinal). Other symptoms may include fatigue, weight loss, unexplained fever, and sometimes night sweats. Gastrointestinal involvement can cause the individual to experience abdominal cramping or bloody diarrhea. Obstruction of the ureter that carries urine from the kidney may produce pain in the flank area (left or right side of the back near the lower ribcage). A history of virus infection (such as infectious mononucleosis or HIV), or Helicobacter pylori infection, may be reported.

Physical exam: Enlarged lymph nodes, nearly always in the neck region or armpit but occasionally in the groin, are usually noted during physical examination. Enlargement of both the spleen (splenomegaly) and liver (hepatomegaly) may be noticed during palpation of the abdomen. Tonsils may be enlarged as well. Bone tenderness or skin lesions may be noted.

Tests: Blood tests will typically be done, including a complete blood count (CBC) to determine red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin level and platelet count. RBCs and hemoglobin may be reduced if anemia is present. WBCs may be elevated as part of the immune system's response to disease or inflammation. A stained differential blood smear may reveal abnormal white blood cells. Blood chemistries such as blood protein (serum albumin), serum protein electrophoresis, and the measurement of liver enzymes will be performed. An erythrocyte sedimentation rate (ESR) may be done to determine if inflammation is present; an ESR is typically elevated in NHL.

Definitive diagnosis of NHL requires a tissue biopsy of an enlarged lymph node; biopsies of other sites that could be involved may be done at the same time or after imaging studies identify specific sites. A section of the tiny piece of tissue removed by needle biopsy will be stained (immunohistochemical staining) and then examined microscopically by a pathologist who will identify cell types; the pathologist will stage the disease at the same time by classifying cells from different sites. The four possible stages for NHL are: I. A single node region or single extranodal site (outside lymph tissue); II. Two or more nodal regions and one extranodal site; III. Nodal disease on both sides of diaphragm, one extranodal site or spleen involvement; IV. Liver, bone marrow, or multiple extranodal sites. Flow cytometry studies may also be performed in addition to routine pathologic examination of cells. Other tests may include routine x-rays (radiographic examination) of the chest, liver, and spleen, and possibly bones, to identify lymphatic tissue that may be involved. Chest x-ray may reveal a mass in the middle of the chest (mediastinal mass). More detailed contrast-enhanced x-ray imaging of the lymph glands and lymphatic vessels (lymphangiography) may be done to determine the extent of lymph node involvement. Computer-aided x-ray analysis (computerized tomography), low-frequency radio waves (magnetic resonance imaging, or MRI), or an exploratory abdominal surgical procedure (laparotomy) may help determine if the cancer is spreading outside the lymph system to other organs. Positron emission tomography (PET) or gallium-67 scintigraphy may be performed to increase the accuracy of staging the cancer. These techniques use radioisotopes to enhance the visualization of biological differences in tumor tissue, allowing more detailed examination than other imaging methods provide. A sample of bone and bone marrow (bone marrow biopsy) may reveal the extent of bone involvement. Ultrasound imaging of the liver may reveal enlargement.