Rocky Mountain spotted fever mimicking acute cholecystitis.

Rocky Mountain spotted fever can present with predominantly abdominal symptoms including nausea, vomiting, diarrhea, and abdominal pain. Two elderly patients presented with an acute febrile illness and abdominal symptoms. Rash was not present initially. Workup disclosed cholelithiasis in one, and a thickened gallbladder wall surrounded by a sonolucent zone suggesting a pericholecystic abscess was found by ultrasonography in the other. Both patients underwent emergency laparotomy, with cholecystectomy in both and appendectomy in one. Both patients died several days postoperatively. Pathologic specimens reviewed later showed that multiple blood vessels of the gallbladder and the appendix were infected with Rickettsia rickettsii, and there was focal vascular thrombosis and hemorrhage. These documented direct rickettsial infections and lesions in the blood vessels of abdominal viscera suggest the basis for the abdominal symptoms in Rocky Mountain spotted fever.