RESUMEN
Infection by Yersinia pseudotuberculosis has become of increasing pathological importance. Patients normally present with symptoms similar to those of appendicitis, due to mesenteric adenitis. We present the case of 3 patients infected by Yersinia pseudotuberculosis who in addition to fever and abdominal pain had a palpable abdominal mass, so great was the enlargement of the mesenteric nodes. In 2 patients a laparotomy was carried out, followed by biopsy of a mesenteric lymph node. The diagnosis of Yersinia infection was confirmed by bacterial culture of the biopsied material and also by serology. In the third patient, serological studies and ultrasonic imaging of the abdomen led to early diagnosis and surgery was avoided. We suggest that a diagnosis of mesenteric adenitis due to Yersinia pseudotuberculosis should now be considered in all patients presenting with an abdominal mass, and in whom there is an appropriate clinical and epidemiological history. The diagnosis should be confirmed by abdominal ultrasound (alternatively Computerised Axial Tomography or Magnetic Resonance Imaging) and serological studies. In this way, unnecessary surgery can be avoided.