RESUMEN
To report a case of fever of unknown origin in a patient with carcinoma of the colon but without gastrointestinal symptoms. Clinical Presentation and Intervention: A 65-year-old man presented with a long-standing fever [of 38°C, about two months' duration], night sweats, fatigue, malaise and anxiety. General physical examination including rectum, radiographic examinations of the chest, abdomen and bones [including ultrasonography and CT scanning] was normal. Biochemistry profile as well as other laboratory studies including blood, urine and stool cultures were normal except for erythrocyte sedimentation rate, which was 105 mm/h. A barium enema showed a rectosigmoid carcinoma. A left sigmoidal colectomy was performed. The patient recovered quickly and remained well for eight years postoperatively. This case shows that carcinoma of the colon should be included in the differential diagnosis of patients with fever of unknown origin