The most common radiographical finding is a single hypodense mass/abscess (68.4%). Extension to surrounding tissues has been evident in 19 cases (33.3%). In Japan, Sugano et al reviewed 11 cases of Actinomyces infection involving the liver. In most patients, there were no predisposing factors. Common symptoms and laboratory findings include fever, abdominal pain, leukocytosis and elevated C-reactive protein. In six of the 11 patients, a partial hepatectomy was performed because hepatic tumour was suspected. Five patients presented with a liver abscess. Hepatic actinomycosis should be considered in the differential diagnoses of pyogenic liver abscess and space-occupying lesions of the liver. Prior abdominal surgery, as well as other disorders that cause a breach of the gastrointestinal tract mucosa, are recognized as risk factors for developing abdominal actinomycosis.
Hematogenous dissemination occurs frequently from thoracic sites, but rarely from other areas. Hepatic abscesses are known to spread to the pleural space; however, direct involvement of the diaphragm and lung is less common. Given our patient’s prolonged abdominal symptoms associated with a previously normal chest radiograph, we suspect that she had direct transdiaphragmatic infection of the lung from a primary infected hepatic site. To our knowledge, only one case report has documented direct invasion of the diaphragm and lung from a primary hepatic infection. CT findings confirmed the infiltrative nature of the disease, showing its tendency to invade across tissue planes and boundaries.
It is well established that actinomycosis often eludes diagnosis, even among the most seasoned clinicians. The infection can be indolent, and obtaining a definitive diagnosis can take up to years. Although speculative, it is interesting to conjecture whether this patient’s infection was related to the cholecystectomy performed five years before presentation.