Biliary actinomycosis, mimesin-common hepatic duct cancer, a rare case report. Actinomycosis is a rare, chronic disease caused by a group of filamentous, gram-positive bacteria that normally colonize oral cavity, gastrointestinal, and orogenital tract. They can become pathogenic when the normal mucosal integrity is disrupted through infections, trauma, or surgery. Actinomycosis of the bile duct is extremely rare and can be cancer or cholecystitis. In general, actinomycosis of the abdominal cavity is a rare disease, and actinomycosis of the biliary tract is even rarer. Only six cases of biliary actinomycosis have been described in the world literature. A 45-year-old woman with no prior comorbidities presented to the emergency with right upper quadrant pain and jaundice. Symptoms appeared three days ago. Ultrasound revealed chronic cholecystitis with bile duct dilation. Radiography of the abdominal cavity showed stones up to 20 mm on the side of the gallbladder. Laboratory analysis revealed leukocytosis, elevated bilirubin, and liver enzymes levels. So, preliminary diagnosis was chronic calculus cholecystitis, common bile duct stones, and mild jaundice. It was planned to perform IRCP-EPT with stone extraction. IRCP revealed dilation of the intrahepatic and proximal common hepatic duct, and 15 mm distance from the confluence there was a stricture of the proximal CHD with no stones in the duct. Because of the stricture, it was decided to perform per-oral transpopillary cholangioscopy. Cholangioscopy using spyglass DE-2 was performed and a semicircle stricture of the proximal CHD was visualized. A cholangioscopy-guided biopsy was performed. It was not possible to pass a cholangioscope through the stricture and visualize bile tree proximally. The intervention was finished by biliary stenting with a 10-frame plastic stand. So, intraoperative diagnosis was unclear stricture of the proximal CHD. A differential diagnosis between Kletzschin's tumor or involvement from the outside was needed. Postoperative period was uneventful. The patient was successfully discharged before the results of the biopsy with recommendations to perform an outpatient MRI. Biopsy revealed strong musculosis of the common hepatic duct that excluded oncology. The patient underwent MRI. There were no signs of external involvement of the biliary tract. On the contrary, a stricture of the terminal CBD was described. These results differed greatly from our results. The patient was recommended to be re-hospitalized for further examination and shorter treatment strategy. Second hospitalization occurred two months after the previous inpatient state. There were no complaints and deviations in laboratory tests. Cancer markers were also within the reference failures. The patient underwent endoscopic ultrasound. There were no stricture described by MRI in the terminal CBD. The stricture of the proximal part of the CHD described earlier was determined. There were also signs of compression of this area from the neck of the gallbladder filled with stones. It was decided to perform cholangioscopy for visual evaluation and repeated biopsy to finally exclude oncology. The previously described stricture was revealed. This time, the cholangioscope was successfully passed through the stricture and proximal biliary tree was observed. An unknown whitish-bluish hollow formation, 3-4 mm in diameter, originated from the right lobe duct was discovered. A biopsy from a newly discovered species area was performed, as well as from the stricture of the carmenhepatic duct for repeated exclusion of tumor growth. Then, restenting was performed. Testological examination of the CHD stricture revealed no differences between the previous one. However, the results from an unknown formation were surprising. Purulent nephrotic inflammation with the presence of actinomycetes was detected. The patient was referred to a specialized institution, the Center for Deep Mycosis and Actinomycosis for Specific Treatment. The patient was prescribed antibacterial therapy, 500 mg of amoxicillin 3 times a day for 6 months. According to the literature, the regression of the infection is a long process. Three months after start of therapy, patient was re-hospitalized in order to assess the dynamics of treatment. HCP and cholangioscopy were performed, and a previously described tubular formation of whitish color was visualized. As we knew what we were dealing with, we ceased and completely removed this formation. After this, an edematous outflow of subsegment duct was determined because of inflammatory changes due to actinomycosis. The CHD stricture remained, so the intervention was ended with a repeated biopsy and stenting. Biopsies revealed fragments of fibrous tissue of the stricture that excluded oncology, and fragments of necrotic detritus without actinomycetes. That demonstrated positive dynamics of treatment. Now the patient continues specific treatment and is planned to perform laparoscopic chelocystectomy with staged endoscopic interventions for fibrous biliary stricture after the finishing of antibiotics. Cell biliary actinomycosis is an extremely rare chronic disease with non-specific clinical manifestations, laboratory, and instrumental changes. Biliary actinomycosis can mimic a malignant neoplasm, which may lead to an incorrect choice of treatment method. Chronic inflammation and rectal fibrosis that occur due to actinomycosis is a reversible process that regresses as a result of prolonged antibiotic therapy. Morphological confirmation is necessary to make correct diagnosis. Cholangioscopy with targeted biopsy made it possible to find the correct diagnosis and choose the optimal patient management tactics.

Biliary actinomycosis

Filamentous bacteria

Chronic disease

Abdominal pain

Jaundice