Serum
carbohydrate antigen 19-9 (CA 19-9), a marker of malignant
tumors, is generally slightly elevated in benign conditions. We report a case of
acute cholecystitis with a significantly elevated level of serum CA 19-9 based on positron emission tomography (PET)-computed tomography (CT) findings. A 65-year-old woman presented with
abdominal pain and
fever. A CT image revealed an enlarged gallbladder without
tumor shadows. The
C-reactive protein (CRP) level was elevated to 7.66 mg/dl. Moreover, the serum CA 19-9 level was significantly elevated to 19,392 U/ml. We started
antibiotic treatment, because we suspected
acute cholecystitis, but still, we could not ignore the possible presence of malignant
tumors. After 11 days of
antibiotic treatment, serum CRP and CA 19-9 levels decreased to 0.11 mg/dl and 1,049 U/ml, respectively. There was an accumulation of
fluorine 18-labeled fluorodeoxyglucose (maximum standardized uptake value, 9.3) without
tumor shadows in the liver, near the gallbladder, on the PET-CT examination. We considered the possibility that the
inflammation had spread from the gallbladder to the liver, made a diagnosis of
acute cholecystitis, and performed a
cholecystectomy 33 days
after treatment initiation. The serum CA 19-9 level decreased to 45 U/ml after the surgery. One year after the surgery, the patient was alive, and the serum CA 19-9 level was 34 U/ml.
Acute cholecystitis with a significantly high elevation of the serum CA 19-9 level is rare. In such cases, it is important to confirm the change in the serum CA 19-9 level over time after
antibiotic treatment and perform imaging studies to distinguish between
inflammation and
malignancy.