Aetiology of pyrexia of unknown origin in north India.

The aetiology of pyrexia of unknown origin (PUO) varies dramatically according to epidemiology. We studied the cause and spectrum of PUO in Indian adults. A total of 152 patients (112 prospectively and 40 retrospectively) met Petersdorf and Beeson's criteria. The diagnostic evaluation was guided by potentially diagnostic clues, based on a 'step-wise' approach. The five main categories, i.e. infectious, neoplastic, non-infectious inflammatory, miscellaneous and undiagnosed comprised 43.4%, 21.5%, 19.7%, 2.0% and 12.5%, respectively. The top three causes were tuberculosis (n = 43, 28.3%), lymphoma (n = 19, 12.5%) and adult-onset Still's disease (n = 12, 7.9%). Tuberculosis predominated in all age groups, and about 70% of cases had the extrapulmonary form, the most common being gastrointestinal. Hodgkin and non-Hodgkin lymphomas were equally distributed, but solid malignancies were uncommon. Adult-onset Still's disease was the second commonest cause in adults aged ≤ 40 years. Fever resolved spontaneously in 12/19 cases of undiagnosed cause. Extrapulmonary tuberculosis remains the most prevalent PUO in India.