Primary Hepatic Actinomycosis Mimicking Hepatic Malignancy with Metastatic Lymph Nodes by F-18 FDG PET/CT

Primary Hepatic Actinomycosis Mimicking Neuroendocrine Tumor

INTRODUCTION

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.

CASE DESCRIPTION

 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.

DISCUSSION

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.

CONCLUSION

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

18F-FDG PET/CT of Hepatosplenic Actinomycosis After Laparoscopic Cystojejunostomy for Pancreatic Pseudocyst

ABSTRACT

We report the 18F-FDG PET/CT appearance of abdominal actinomycosis in a 48-year-old immunocompetent woman with a history of laparoscopic cystojejunostomy for pancreatic pseudocyst previously. 18F-FDG PET/CT demonstrated multiple hypermetabolism in the liver, spleen, cystojejunostomy anastomosis, greater omentum, and umbilical region. Actinomycosis was verified by biopsy. Hepatosplenic actinomycosis secondary to cystojejunostomy is extremely rare and easily to be misdiagnosed. PET/CT is helpful for auxiliary diagnosis, guiding biopsy, and exploring the extent of the disease.

Hepatic actinomycosis with immunoglobulin G4-related liver disease: A case report

RATIONALE

Immunoglobulin (Ig)G4-related pseudotumors of the liver are very rare diseases that are difficult to distinguish from malignant tumors. They can be usually improved by steroid therapy. Actinomycosis is a chronic, suppurative, granulomatous infection, for which immune suppression is a predisposing factor. It can also mimic malignant tumors.

PATIENT CONCERNS

A 67-year-old man presented with mild abdominal discomfort and a 5-kg weight loss for 3 months. Initially, he visited another hospital and was treated with antibiotics under the assumption of a liver abscess. Symptom was not resolved.

DIAGNOSES

He diagnosed as having an IgG4-related pseudotumor of the right lobe of the liver after liver biopsy. Despite 2 months of steroid therapy, the liver mass was aggravated and invaded the right lung, as observed on follow-up computed tomography scan.

INTERVENTIONS

We performed en bloc resection of the tumor under the assumption that it was a malignant tumor.

OUTCOMES

The pathology of the tumor was revealed as actinomycotic colonies and IgG4-positive plasma cells of the liver. He recovered well and was discharged with ursodeoxycholic acid tablet for 14 days. After 3 months, he underwent postoperative follow-up CT and there was no remarkable finding in remnant left hepatic lobe.

LESSONS

Hepatic actinomycosis and IgG4-related pseudotumors of the liver are both difficult to diagnose. As in our patient, combined diseases are more difficult to diagnose and to determine the optimal treatment. Since immunosuppression therapy of autoimmune diseases can cause and aggravate infection, management must be approached carefully. We can learn that various possibilities must be considered before diagnosing and treating a hepatic mass.