Cytopathology of Hepatobiliary-Related Actinomycosis

Background: The clinical diagnosis of hepatobiliary-related actinomycosis can be challenging owing to its rarity and variable presentation. Moreover, actinomycotic pseudotumors may mimic malignancy and result in unnecessary surgical resection. Herein, we present the clinical and cytopathological features of 3 cases with hepatobiliary-related actinomycosis. Cases: The first patient was a 73-year-old man who presented with an exophytic liver lesion. The second patient was a 78-year-old woman who presented with a biliary stricture. The third patient was an 88-year-old woman with a right flank mass extending to the liver. The aspirate smears in these 3 cases demonstrated 'cotton ball' clusters of filamentous microorganisms and abscesses. The cell blocks of 2 of the patients showed sulfur granules with peripheral filamentous microorganisms positive with a Gram stain but negative with an acid fast stain, consistent with Actinomyces species. All patients were elderly and shared a past surgical history of laparoscopic cholecystectomy. Conclusion: These cases demonstrate the complementary role of cytology in the diagnosis of hepatobiliary actinomycosis. A cytologic diagnosis of actinomycosis is minimally invasive and quick. It can prompt proper culture medium selection and avoid unnecessary or extensive surgery. Based on our experience, laparoscopic cholecystectomy may be a precipitating factor for the subsequent development of hepatobiliary-related actinomycosis.