A rare complication of acute acalculous cholecystitis following abuse of transdermal fentanyl for the treatment of failed back surgery syndrome

A 65-year-old man presented with uncontrolled severe low back pain and both leg pain (VAS 9) due to failed back surgery syndrome confirmed by magnetic resonance imaging. We prescribed transdermal fentanyl patch (25 μg/h) for pain relief, and at 2 weeks later, symptom was lessened (VAS 4). But after 1 month, he was admitted to our emergency department for nausea, vomiting, and right upper quadrant (RUQ) pain occurring 3 days and aggravating 4 h before arrival. He used 2 patches (50 μg/h) without prescription for the purpose of relieving breakthrough pain for 2 weeks. After subsidence of pain, he applied TDF with same dose. On physical examination and radiologic assessment, he was diagnosed as acute acalculous cholecystitis. To the best of authors’ knowledge, there have been no reports about acute acalculous cholecystitis after abuse of TDF. On the diagnosis of acute acalculous cholecystitis (AAC), laparoscopic cholecystectomy was performed. Gangrenous change of GB was found on pathologic specimen. Severe abdominal pain was relieved after surgery. Acute acalculous cholecystitis can occur as a rare complication after abuse of TDF.