Teaching Case

A 45-year-old man presented with sharp abdominal pain, vomiting, and fever for 20 days. He also complained of weakness and weight loss (5 kg) in one month. His laboratory investigations, including white cell count and CRP, were on high levels. No history of medication or stigmata for chronic liver disease were identified.

Abdominal ultrasonography showed a well-defined heterogeneous mass located in the right hepatic lobe. The texture of the mass was hypoechoic heterogeneous, without hypervascularization at colour Doppler, with discrete posterior reinforcement. (Fig. 1)
A triple phase contrast CT was performed and showed a well-defined heterogeneous mass in the right hepatic lobe, measuring 11 cm in greater axis, hypodense in spontaneous contrast, with moderate peripheral enhancement in the portal and late phases, including septa giving a mutilocular appearance. There were liver perfusion disorders. (Fig. 2)
In view of the appearance on imaging and clinical presentation, the patient was treated with antibiotics, but without therapeutic response. Ultrasound-guided biopsy was performed. A histological diagnosis of inflammatory pseudotumour of the liver was made, and the patient was treated by corticosteroids, with good clinical and radiological response. (Fig. 3)

Inflammatory pseudotumour (IPT) is a rare benign tumour, which may develop in various organs, most common in orbit and lung. Liver location is rare, and was the subject of some publications on very limited series. In the World Health Organisation classification, it is defined as a fibroblast proliferation, infiltrated with polymorphous inflammatory cells (plasma cells, lymphocytes and histiocytes). [1]
In the literature, they have been reported under different names: granuloma plasma cells, inflammatory myofibroblastic tumour and histiocytoma. They include very atypical clinical and radiological entities that can mimic a true neoplastic involvement.
Their preoperative diagnosis is difficult, and is usually rectified by histological examination of biopsy, or surgical specimen.
Although the pathogenesis is still unclear, it has been postulated that the disease may be related to portal venous infection, producing an inflammatory mass in a gradually expanding way, with granulomatous inflammation. Some bacteria including Escherichia coli, Staphylococcus aureus, and Gram-positive cocci have been proposed as the causative agents. [2, 3]
Patients present with fever, weight loss, thrombocytosis, iron deficiency anaemia, hypergammaglobulinaemia, or symptoms related to mass effect. [5]
The radiologic features of IPT are variable and nonspecific, related to varying amount of fibrosis and cellular infiltration.
On ultrasound images, lesions can be hypoechoic or hyperechoic with ill-defined or well-circumscribed borders. CT also shows varying appearances: unenhanced images show the tumour’s hypoattenuating liver parenchyma, and contrast administration reveals variable contrast enhancement. They may present with hypovascular character because of fibrosis. [6, 7] The MRI may produce low signal intensity on T1-weighted images with moderate to high signal intensity on T2 sequence, with variable contrast enhancement. [5, 4] Delayed imaging often shows increasing enhancement due to the presence of fibrosis. [5, 4]
Differential diagnosis include malignant tumour and liver abscess.
Hence, knowledge of hepatic IPT can prevent incorrect diagnosis, and percutaneous needle biopsy is important to avoid unnecessary exploratory laparotomy or hepatectomy. If the pathologic features are known to be present and malignancy has been excluded, conservative management is appropriate, and patients can be treated with steroidal or non-steroidal anti-inflammatory drugs [1, 5].
Although uncommon, IPTs of the liver have been increasingly recognized in recent years, mainly in a biopsy or resection specimen. In conclusion, if an atypical solid mass is found in the liver, IPT should be considered as a diagnosis, particularly if the mass is accompanied by a clinical inflammatory process, or intermittent fever; absence of stigmata of chronic liver disease; abnormal liver function test results; and a lack of specific imaging findings. [7]