Fever of Unknown Origin: A Patient with Intermittent Idiopathic Fever for Three Years

Fever of unknown origin (FUO) is defined as a fever ≥38.3 ºC on at least three occasions over a period of at least three weeks, with no obvious diagnosis despite one week of inpatient investigations. Over 200 infections, neoplasm and inflammatory diseases can lead to an FUO. The definition of FUO is difficult, even though more sophisticated diagnostic tools such as positron emitted tomography and many biochemical and serological assays have become routinely available. However, it is surprising that despite the improvement in diagnostic modalities, some FUO still remain undiagnosed. When the diagnosis of FUO was not defined, invasive tests such as biopsies may be useful. Bone marrow biopsy is an accepted method in FUO to uncover haematological malignancies and certain infections. We report a case of prolonged fever 4-5 times each year for 3 years which has presented FUO. She had bone morrow biopsy and was diagnosed with T-cell large granular lymphocytic leukaemia.