The key to understanding lymphoma as a secondary condition to primary lymphedema is in the pathophysiology of the lymph system.
In the situation of primary lymphedema, the lymph system is either incompletely formed or malformed. This means that the spread of and the expression of lymphoma (course of the disease) is going to be different then in an individual with a "normal" lymph system.
The reason is simple. With the lymphatic flow constricted, the malignancy will have a more difficult time spreading to external nodal areas. The incomplete lymph system will act as a "damn" actually helping to contain the lymphoma.
Beause of either the hypoplaysia or hyperplaysia of the lymphatics, it is going to be more difficult to obtain an accurate diagnosis of a lymphtic cancer.
Case in point.: The nodes of a person with lymphedema may already be smaller then normal. Therefore, if there is limited nodal enlargment (or even if there is none) you can not assume no malignancy is present.
Furthermore, I have yet to experience really significant lymph node enlargement. But, what I have experienced are nodes that are only slightly larger then "normal" yet have turned hard and rubbery.
Standard radiological tests must be viewed carefully in using them to chart lymphatic cancer with lymphedema. MRI's and CAT's are of limited use as the "normal" size node they are picking up, may infact be malignant.
Case in point: When the small needle biopsy of my right inguinal lymph node was performed, the doctor did an ultrasound first. That node looked perfectly normal to the ultrasound. The biopsy came back positive.
The use of a PET scan in the staging and diagnosis must be viewed with skepticism. There are important reasons for this. The principle behind the PET is quite simple. Tumor (malignancies) will have a higher metabolic rate then the surrounding nonmalignant tissues. Therefore, the malignancies will have a higher "uptake" of the contrast used.
Because of the dysfuntion of the lymph system, it is going to be more difficult for the contrast to make its way through the body and be absorbed. This will effect the diagnostic effectiveness.
Unfortunately too, there is also no standard uptake value for tissue effected by lymphedema. Therefore, it is going to be difficult to ascertain whether a SUV number indicates a malignancy or not.
On the opposite side, lymphedema patients are faced with constant inflammation and/or chronic low grade infection. Both of these can give a false positive to a PET scan.
After the diagnosis of a lymphatic cancer is achieved, the treating physician must carefully monitor changes in the complications experienced by the patient. New complications and changes must not automatically be assumed that they are caused by lymphedema.
Case in point : Before the spread and/or infilitration of lymphoma throughout my system, I did not have lung fluid. Two years ago, I began having fluid accumulate in my right lung. This year, the left lung has also been extensively involved.
Also, my lymphedema has been consistent for decades. Also, during the past two years, I have experienced swelling of my left arm for the first time.
It is important to understand that those of use with a dysfunctional lymph system walk a fine line. In my situation, with an already at risk lymph system, the lymphoma spreading through the chest was enough to "overload" the impaired system resulting in both pleural effusions and swelling of the left arm.
Perhaps the most important point to make is for the physician to "listen" to the patient. Individuals like myself have lived with lymphedema for decades - most for years.
We know how lymphedema effects our bodies, what is (normal) for ourselves and what should or should not be happening.
Listen...care about...communicate with your patient.