Septic thrombophlebitis of the porto-mesenteric venous system, also called pylephlebitis, is a rare pathological entity with significant mortality and morbidity, secondary to an intra-abdominal infectious process. Due to the poor specificity of the clinical and laboratory findings, it is usually underestimated, being a diagnosis made mainly radiologically, potentially treatable, with a reduction of its complications, only after an early diagnosis. We present a case of a 50-year-old male patient, undergoing a radiological evaluation for a gastric neoplasia, with an incidental finding of pylephlebitis secondary to acute appendicitis, successfully treated with intravenous antibiotic therapy, anticoagulation and emergency laparotomy.