Abdominal actinomycosis is a rare granulomatous infection caused by Actinomyces bacteria, typically presenting as fistulas, abscesses, or masses. Delayed diagnosis
may hinder timely treatment, making early detection crucial.
A 60-year-old male with no significant medical history presented with obstructive
jaundice due to a hilar mass involving the right bile ducts and the origin of the
left bile duct (Klatskin type III A). Suspecting malignancy, a percutaneous biopsy
was performed, yielding negative results. Endoscopic ultrasound (EUS) was attempted
but failed due to insufficient access to the duodenal bulb. An exploratory laparoscopy
revealed an inflammatory mass, which hindered proper sample collection.
In a second EUS, the duodenal bulb was accessible, and a poorly defined mass was identified
in the hepatic hilum, involving the porta hepatis and adjacent to the hepatic artery.
Elastography showed a blue pattern suggestive of malignancy. After two needle passes
using a 22G biopsy needle and the "slow pull" technique, histopathological analysis
revealed branching basophilic structures (PAS and silver stain positive), consistent
with Actinomyces and no malignancy. Targeted antibiotic therapy was initiated, leading to a reduction
in mass size and clinical improvement.
Biliary actinomycosis, often mistaken for malignancy due to its rarity, should be
included in the differential diagnosis of abdominal masses. A comprehensive diagnostic
approach, including EUS, is vital for effective identification and treatment.
