Giant infected splenic pseudocyst complicated by rupture in a patient with chronic Q fever

Giant infected splenic pseudocysts are rare and may be difficult to diagnose due to overlapping clinical and imaging features with other cystic splenic lesions, including hydatid cysts and abscesses. At our institution, a 59-year-old male with no reported history of splenic trauma presented with weight loss, early satiety, and left upper quadrant pain. Computed tomography demonstrated a large calcified splenic cyst measuring up to 14.6 cm with internal septations and an air-fluid level, concerning for infection and rupture. The cyst fluid measured a median of 12 Hounsfield units, without perceptible wall or septal enhancement. Ultrasound demonstrated complex internal debris and septations without internal vascularity. Serologic testing showed markedly elevated Coxiella burnetii titers, and splenic tissue polymerase chain reaction testing was positive. The patient underwent pre-operative splenic artery embolization followed by open splenectomy. Intra-operatively, the cyst ruptured with the release of purulent material without fistulous communication. The postoperative course was complicated by a pancreatic leak and a subsequently identified transverse colonic defect, managed with segmental colectomy and end colostomy. Histopathology demonstrated a fibrous cyst wall without epithelial lining, consistent with a pseudocyst. This case expands the recognized spectrum of complicated splenic pseudocysts, with rupture and polymicrobial superinfection occurring in the setting of concordant serologic and molecular evidence of C burnetii.