Peripheral lymphadenopathy in immunocompetent adults.

Although unexplained lymphadenopathies are not particular prevalent in the general population (<1%), they represent a diagnostic dilemma. The differential diagnosis is broad, and although only few diseases will be either severe or treatable, patients as well as their doctors are in fear of missing a relevant diagnosis such as a malignancy. For the differential diagnosis it is prudent to distinguish between localised and generalised lymphadenopathy. Seventy-five percent of all lymphadenopathies are localised and often caused by a specific pathology in the area of drainage, which can be diagnosed without additional investigations. If the diagnosis is unclear, the patient is clinically stable and there is no suspicion of malignancy, it is safe to wait for three to four weeks and observe the clinical course. Exceptions are supra- and infraclavicular lymph nodes, which are always suspicious of an underlying malignancy. Twenty-five percent of lymphadenopathies are generalised and are often a sign of a significant underlying disease. A diagnosis of lymphoma, malignancy, HIV infection or tuberculosis should not be missed. Excisional biopsy is regarded as the diagnostic method of choice, since it allows an assessment of the architecture of the lymph node as well as histological, immunohistochemical, cytogenetic and molecular investigations.