Primary Hepatic Actinomycosis Mimicking Neuroendocrine Tumor

The Actinomyces species is a fastidious, gram-positive, non-spore-forming bacteria that thrive in microareophilic and anaerobic conditions. Infection in the liver, an organ rarely affected by this pathogen, is presumed to be caused by hematogenous spread through the portal vein from a mucosal injury or other abdominal injury or a focus of infection.

A 60-year-old male patient has a mass lesion of 15 × 10 cm in the left lobe on computed tomography. A tru-cut biopsy was performed with USG, and fragmented tissue pieces were obtained. In histopathological examination, these samples were reported as tumors with neuroendocrine differentiation. The biopsy sample contains a large amount of tumor neighborhood, and tumoral area is quite small. And, therefore, a clear diagnosis could not be found. A mass lesion with mildly increased Ga 68 DOTATATE uptake was observed in the left lobe of the liver (SUVmax value 3.8) and was interpreted in favor of the primary neuroendocrine tumor of the liver.

Actinomyces cases are very rare and their diagnosis is usually delayed due to its slow and insidious course, and lack of specific clinical and radiological findings. It is difficult to make a correct diagnosis even in microbiological examinations and biopsy materials obtained in the presence of imaging methods. It can mimic tumors of abdominopelvic structures.

Actinomyces should be kept in mind in cases with liver masses accompanied by previous abdominal surgery, abdominal trauma, high fever, and leukocytosis.