Actinomycosis of the Common Bile Duct Diagnosed by Endoscopic Ultrasound Fine-Needle Aspiration

Endoscopic ultrasound (EUS) is a useful modality for examining the pancreaticobiliary system, as it provides high-resolution images without interference from bowel gas and fat. EUS fine-needle aspiration (FNA) has contributed greatly to the diagnosis of hepatobiliary and pancreatic diseases. In this case report, we present a patient with hepatobiliary actinomycosis diagnosed by EUS. Actinomyces are gram-positive, beaded, filamentous, anaerobic bacteria that form chronic granu-lomatous lesions and suppurative abscesses. These bacteria frequently colonize the upper respiratory, gastrointestinal, and female genital tracts but rarely invade the hepatobiliary system in the absence of gastrointestinal surgery or trauma to the bowel.

Case Report

A 64-year-old Jamaican woman with no significant medical history presented to another institution with a 2-month history of jaundice, weight loss, itching, and right upper quadrant discomfort. An abdominal computed tomography (CT) scan revealed an enhancing soft tissue mass that involved the gallbladder fossa and extended from the pancreatic head to the porta hepatis (Figure 1). An intrauterine device (IUD) was also identified. The patient underwent an endoscopic retrograde cholangiopancreatography, which revealed a stented mid–bile duct stricture. Suspicious cells were found from the common bile duct (CBD) brushing. The patient presented to our institution 1 month later with persistent right upper quadrant abdominal pain. Laboratory examination revealed a white blood cell count of 6.0 × 10³ cells/mm³, aspartate aminotransferase level of 28 U/L, alanine aminotransferase level of 34 U/L, alkaline phosphatase level of 265 U/L, total bilirubin level of 0.9 mg/dL, and direct bilirubin level of 0.4 mg/dL. The patient's CA 19-9 level was unremarkable. EUS revealed a 4.5-cm × 4.3-cm heterogeneous isoechoic mass abutting the portal vein and CBD, extending from the proximal pancreas to the porta hepatis (Figure 2). EUS-FNA revealed reactive ductal hyperplasia with actinomycotic organisms and atypical ductal cells.

Figure 1.

Computed tomography scan showing a soft tissue mass (arrows) in the gallbladder fossa.

Figure 2.

Endoscopic ultrasound showing a heterogeneous isoechoic mass abutting the portal vein (PV) and common bile duct (CBD). A stent (st) is also present.

The patient underwent removal of her IUD and began treatment with ceftriaxone sodium (Rocephin, Hoffman-La Roche), which was changed to doxycycline upon development of toxic epidermal necrolysis. Despite the use of antibiotics, the mass increased in size, and a laboratory examination revealed worsening biliary obstruction (evidenced by increases in alkaline phosphatase level to 693 U/L, total bilirubin level to 8.0 mg/dL, and direct bilirubin level to 5.3 mg/dL). The patient subsequently underwent a cholecystectomy and hepaticojejunostomy. Surgical pathology revealed acute inflammation, with a foci of papillary carcinoma in the CBD.

Discussion

Actinomycosis is a rare disease characterized by a chronic, progressive, granulomatous infection caused by the Acti-nomyces species, of which Actinomyces israelii is the most frequently isolated.¹ Actinomyces are gram-positive, micro-aerophilic or obligatorily anaerobic filamentous bacteria endogenous to the oral cavity and the genitourinary and gastrointestinal tracts.^2–4 These bacteria are opportunistic and lack virulence; therefore, disease typically follows an indolent course that may last several years.⁴ Penetration and propagation occur through contiguous spread in immunocompromised states or upon breaching the normal barrier.^2,4–6 Due to the large filaments of the cells, lymphatic spread is rare. Hematogenous spread to the liver is a rare but serious complication.¹ The characteristic granulomatous inflammatory response is followed by necrosis and extensive fibrosis, with fistulization as a common late outcome.⁶

Long-term IUD use is a known risk factor for developing pelvic actinomycosis.^7,8 On rare occasions, local endometritis can progress to an ascending infection with intra-abdominal abscesses.⁸ In one study, the colonization rate of vaginal flora with Actinomyces was 11.4% in patients with an IUD.⁹ Approximately 0.5–1.0% of patients with an IUD develop actinomycosis, particularly after the device has been in place for at least 3 years.⁸ This diagnosis should be considered in any woman with an IUD who presents with abdominal pain and an abdomi-nopelvic mass on imaging.

Actinomycosis occurs most frequently in the cervi-cofacial (50%), abdominal (20%), and thoracic (15%) regions.^2,5 The incidence of abdominal disease is 0–3 cases per year in the United States.¹⁰ Abdominal actinomycosis may present as a mass lesion mimicking malignancy, diver-ticular abscess, tuberculosis, or Crohn's disease. Diagnosis is often made only during surgical exploration.^4,7,8,11 Abdominal actinomycosis typically occurs after gallbladder, appen-diceal, or colonic surgery, with the appendix and ileocecal valve comprising the most common sites of infection.^4,12

Hepatobiliary actinomycosis is extremely rare and may present as acute or chronic cholecystitis, biliary colic, or pancreatitis.^2,13 Liver involvement is reported in only 5% of patients.¹⁴ Involvement of the gallbladder is rare; to our knowledge, only 18 cases have been reported in the literature.¹ Isolated actinomycosis of the CBD without liver or gallbladder involvement has been reported in 1 case.¹⁵ The proposed pathogenesis of hepatobiliary acti-nomycosis is retrograde spread from the duodenum into the CBD.^1,12,15

There is no pathognomonic radiographic sign of actinomycosis. However, CT frequently reveals infiltra-tive, enhancing areas of decreased attenuation, with contrast invading surrounding tissues.^1,4,11 Ultimately, tissue biopsy is necessary for diagnosis.

Once actinomycosis is diagnosed, prolonged antibiotics are required due to reactive fibrosis formed by the bacteria.² Recommended first-line treatment consists of a penicillin–derivative drug administered over 6–12 months. Alternative treatments include tetracycline, erythromycin, clindamycin, or doxycycline.^4,12 Surgery is indicated for debridement, removal of sinus tracts, and fistula repair.^2,4 To our knowledge, carcinoma of the gallbladder has only once been reported in association with actinomycosis of the gallbladder.¹³