Lymphoma refers to the cancer that is derived from lymphocytes, which is the type of cell that makes up part of the immune system. Lymphoma is usually shows presence within solid tumors of lymphoid cells. The malignant cells formed typically originate within lymph nodes and shows presence as an enlarged node (usually a tumor). Common sites of lymphoma include the skin, brain, bone, and bowels.
Usually, an excisional biopsy is utilized to test for lymphoma. The biopsy sample is then observed by a pathologist to determine if there are any signs of lymphoma. The biopsy is usually obtained from the lymph node, but there may be cases in which the patients experience lymphoma effects in areas such as the skin, brain or stomach. Needle aspiration tests are also performed for diagnosis. When the lymphoma is diagnosed, further scans and image tests are utilized to observe how far the cancer has spread.
Signs and Symptoms 
These warnings can be subtle and may take some time before serious affects occur.
Painless lumps in your neck, armpits or groin This is the most common noticeable symptom and often the only one. The painless lumps are actually enlarged lymph nodes. A doctor should observe these lumps as these enlarged nodes may not always be a sign of lymphoma.
Weight loss This can occur rapidly for no apparent reason. An individual can lose up to ten to 15 pounds over a period of a couple months.
Fever Continuous fever or a reoccurring fever over a period of time may be a good sign of lymphoma symptoms, as long as they don't seem related to a urinary or chest infection. Fevers related to node swelling occur often with infections, which individuals may mistake as lymphoma at an early stage. Individuals with Hodgkin lymphoma undergo a characteristic fever called a Pel-Ebstein fever.
Excessive sweating at night Waking up in the middle of the night drenched in sweat without any apparent reason can be a symptom of lymphoma. Excessive itchiness all over ones body can also occur. These symptoms are due to the secretion of some special chemicals from the lymphoma cells.
Loss of appetite A loss of appetite can occur as the lymphoma cancer cells spread within an individuals body, often leading to weight loss.
A feeling of weakness A feeling of weakness occurs due to the growing of cancer cells. These cells use up the body's nutrients, leaving the body with little energy to work with.
Lymphoma can occur in any organ, causing pain in the affected area. For example if the lymphoma was found int he stomach, pain may occur in the abdomen. If a lymphoma was found in the brain, serious headaches or leg weakness could occur as well.
Treatment of lymphoma include chemotherapy, radiotherapy, and/or bone marrow transplantation. These processes do not cure lymphoma, but have the tendency to alleviate the symptoms of it. Lymphoma can be curable depending on the histology, type, and stage of the disease in the individual.
1. "How is Lymphoma Diagnosed?" <http://lymphoma.about.com/od/testsforlymphoma/p/diagnosis.htm> 2. Indranil Mallick, M.D., December 02, 2010. <http://lymphoma.about.com/od/symptoms/tp/warningsigns.htm> 3. <http://en.wikipedia.org/wiki/Lymphoma#cite_ref-9>