The authors report the case of a 14-year old male seen at the adult emergency room at Hospital da Restauração, presenting acute inflammation in the abdomen, secondary to acute appendicitis with local peritonitis. On the 8th postoperative day, he returned to the hospital with abdominal pain associated with fever and intense leukocytosis. Abdominal ultrasonography showed distended gallbladder with thickened walls, which suggests acute acalculous cholecystitis. The patient was submitted to surgery, which revealed an enlarged vesicle, thickened walls, and no calculi inside it. After theperformance of cholecystomy, the patient was dismissed on the 4th postoperative day. Os autores relatam o caso de um paciente de 14 anos, masculino, atendido na emergência de Adultos do Hospital da Restauração, com quadro de abdômen agudo inflamatório, secundário a apendicite aguda com peritonite localizada. No oitavo dia de pós-operatório, retornou ao hospital com dor abdominal associada à febre e intensa leucocitose. A ultra-sonografia abdominal revelou vesícula biliar distendida com paredes espessadas, sugestivo de colecistite aguda alitiásica. O paciente foi submetido à cirurgia, com achado de vesícula aumentada de volume, paredes espessadas, sem cálculos em seu interior. Realizada colecistectomia, tendo alta hospitalar no quarto diade pós-operatório.