[Clinical reasoning and decision making in practice. A 41-year old with periodic fever of unknown origin].

A 41-year-old man presented with unexplained bleeding from the right tonsil. He subsequently developed periodic fever, cervical lymphadenopathy and hepatosplenomegaly. Despite extensive bacteriological, serological and radiographic investigations for infectious disease, rheumatic disease and malignancy no diagnosis was made. Although the fever pattern was very suggestive of Pel-Ebstein fever--commonly associated with lymphoproliferative disease--multiple biopsies of lymph nodes, bone marrow, tonsils and liver all proved negative. Empirical glucocorticoid therapy gave some temporary improvement lasting for a month. Splenectomy or splenic biopsy was not carried out because of the risk of excessive bleeding. Eventually the patient died of multi-organ failure and sepsis. At autopsy, a T-cell lymphoma with an unusual phenotype and focal involvement of bone marrow, liver and spleen was found. Clinicians are sometimes faced with the dilemma of whether to perform multiple, invasive and possibly harmful diagnostic tests or to start empirical therapy. Empirical therapy may only be started if the diagnosis has been made on strong clinical grounds and, if this is not the case, only after further diagnostic tests. The question of whether a potentially harmful diagnostic test is justified depends on the clinical course, the sensitivity and specificity of the test and the therapeutic possibilities.