1256 Cystoisospora belli Infection of the Gallbladder: More Common Than You May Think

Abstract

INTRODUCTION: Cystoisosporiasis is an underrecognized gallbladder infection of immunocompetent hosts due in part to subtle histopathologic findings and low index of suspicion during examination of routine cholecystectomy specimens. This case will highlight the importance of detecting the organism in order to gain understanding of its life cycle and to raise awareness of the potential symptoms for those who become immunosuppressed. CASE DESCRIPTION/METHODS: A 65-year-old male with compensated cirrhosis presented with complaints of intermittent right upper quadrant pain for three months. He denied symptoms of diarrhea, jaundice, fever, chills, recent travel and sick contacts. CBC, BMP and liver enzymes were unremarkable. A right upper quadrant ultrasound illustrated multiple gallstones within the gallbladder along with wall thickening measuring up to 4.8 mm. The patient underwent a laparoscopic cholecystectomy with resolution of symptoms. Pathologic evaluation of the resected gallbladder described elongated “banana-shaped” zoites of C. belliwithin parasitopherous vacuoles in the gallbladder columnar mucosa. DISCUSSION: Cystoisospora belli (C. belli) is an intracellular protozoan of the intestinal epithelium often associated with gastrointestinal (GI) disease in immunocompromised patients or those who travel to endemic areas. The infection is acquired by fecal-oral route through ingestion of infective oocysts in contaminated water. Symptoms of C. belli include watery diarrhea, abdominal pain, nausea, vomiting and weight loss due to malabsorption, whereas most infected immunocompetent patients remain asymptomatic. C. belli is known to reside within parasitophorous vacuoles in epithelial cells of the small intestine; however, incidence of gallbladder infection is on the rise as there becomes an increased awareness and recognition on the part of the pathologist. Previously, lack of recognition has stemmed from multiple factors including a low index of suspicion in patients without clinical symptoms or those who remain immunocompetent, the underwhelming appearance of infected gallbladders with lack of significant tissue reaction, as well as the sparse distribution of the organisms themselves. The unexpectedly high prevalence in gallbladder specimens has given rise to the idea that the gallbladder may be an anatomic reservoir for this commensal organism in the immunocompetent host. For this reason, C. belli infection should be considered in patients exhibiting typical GI symptoms following immunosuppression.