title: Extra-skeletal Ewing's sarcoma resembling acute abdomen. Case report.
abstract: BACKGROUND
  Extraosseous Ewing's sarcoma is a rare tumor of neuroectodermal origin. It presents mainly in the soft tissue of the extremities and thorax. Histologically, it is similar to Ewing's sarcoma of the bone.
  
  
  METHODS
  We present the case of a male who arrived at the emergency room with acute abdomen, leucocytosis and imaging techniques (abdominal ultrasound and computed tomography) suggestive of complicated diverticular disease. He was treated with emergency surgery. Intraoperative findings were an unsuspected tumor (20 x 15 x 15 cm). Treatment consisted of extirpation of the tumor, separating it from the adjacent viscera and followed by chemotherapy based on epirubicin, cyclophosphamide and vincristine for six cycles. Because the control abdominal CT demonstrated tumor activity in the retroperitoneum adjacent to the ascending colon and cecum, further resection was decided upon.
  
  
  CONCLUSIONS
  In a review of the literature, no previous reports of extraosseous Ewing's sarcoma were found presenting as acute abdomen. Due to the rarity of this tumor, only case reports or series have been found in the literature without randomized or comparative studies. Surgery was the cornerstone of treatment, without reports of preoperative chemotherapy. If the patient's condition permits, percutaneous needle biopsy is mandatory to obtain optimum treatment as well as to improve prognosis.
authors.affiliation: Departamento de Cirugía General, Hospital General Regional 1 Gabriel Mancera, Instituto Mexicano del Seguro Social, México, DF, Mexico. guzvaldi@yahoo.com
authors.forename: Gilberto Guzmán
authors.initials: GG
authors.lastname: Valdivia Gómez
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Soto Guerrero
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Cedillo de la Cruz
mesh_terms: D000006:Abdomen, Acute / Q000175:diagnosis*; D000328:Adult; D003937:Diagnosis, Differential; D006801:Humans; D008297:Male; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis*; D012512:Sarcoma, Ewing / Q000175:diagnosis*