HCC occasionally grows outside the liver in a pedunculated form, hence making preoperative diagnosis difficult [1, 2]. To differentiate P-HCC from other exophytic benign and malignant liver tumors is not always absolute, particularly when other pathological hepatic lesions coexist [6–9]. Benign pedunculated tumors such as focal nodular hyperplasia, liver cell adenoma, hemangioma and angiomyolipoma often pose a diagnostic challenge due to uncertainty of the nature of the tumor [7]. As for malignant tumors, the differential diagnosis is occasionally difficult in cases of exophytic growth of an HCC protruding caudad from the right lobe of the liver, which may show retroperitoneal extension, thus mimicking a right adrenal tumor [10, 11]. Similarly, pedunculated HCC may invade the duodenum and mimic a duodenal gastrointestinal stromal tumor [6]. Although the use of various imaging modalities such as CT and MRI can demonstrate the presence of the tumor itself, making a correct diagnosis is often challenging for radiologists because of the uncertainty of tumor origin [6, 12]. The characterization of the nature of these tumors is of primary importance for their management and treatment. Specific imaging features, such as "prominent feeding artery sign", dynamic diffuse enhancement pattern during hepatic arterial phase, and fatty components are useful for identifying the origin and nature of liver tumors [6, 8, 9].
In the present case, the patient was aware of a liver mass of unknown nature, which was asymptomatic for over 10 years. Due to idiopathic hemochromatosis, the patient had regular follow-up investigations with ultrasound and CT, suggesting an exophytic mass arising from the inferior surface of the right lobe of the liver, and with imaging features characteristic of hemangioma. It is reported that Idiopathic hemocromatosis is associated with an increased risk for hepatocellular carcinoma [13, 14]. The risk has been estimated to be as high as 200-fold increased and occurs predominantly in patients with cirrhosis at the time of diagnosis. Even if excess iron has been removed by phlebotomies, the risk of HCC persists once cirrhosis has been established. Iron overload per se might also contribute to the development of HCC. In the case of our patient, the liver parenchyma from the surgical margin of tumor pedicle exhibited features of mild reactive non-specific hepatitis, signs of portal venous stasis and mild microvesicular steatosis. No cirrhosis or iron deposition signs were present. Furthermore, iron has successfully been depleted by phlebotomies, so excessive iron deposition could not be detected in liver parenchyma by histology examination. Other cofactors that might promote the development of HCC in hemochromatosis, such as viral hepatitis, excessive alcohol intake etc. were also absent. In literature, do not exist reports on a potential association between the specific subtype of P-HCC and idiopathic hemochromatosis.
This patient unfortunately experienced a severe allergic reaction to radio-opaque medium during CT examination in the past and all CT and MRI studies were performed without administration of contrast medium. Therefore, typical enhancement patterns of the exophytic HCC could not be identified. It is well known that, most hepatic hemangiomas identified on CT or MRI can be diagnosed accurately from the characteristic imaging features of these lesions. On T1 weighted (T1W) images are hypointense to surrounding hepatic parenchyma with smooth, well-defined, often lobulated margins. On T2 weighted images (T2 W) they become significantly hyperintense compared to normal liver. In this case of a giant pedunculated HCC with hemangioma the MRI was not characteristic. According to Bader TR et al. [7], the exophytic benign tumors of the liver, on preconstant images, signal intensity was regarded as isointense, hypointense, or hyperintense in comparison to normal liver parenchyma. However, in our case, the heterogeneous nature of tumor mass resulted in a different imaging appearance on MRI.
The patient's condition had shown a gradual deterioration in the previous 6 months, accompanied by general malaise, anorexia, severe weight loss, and persistent right hypochondrial pain. At admission, MRI examination showed an increased size of the pedunculated liver mass that appeared hyper-dense on T1-and T2- weighted images, with the central portion of the tumor showing a high signal intensity area compatible with central necrosis. Although the imaging studies could not draw a definitive diagnosis of the nature of the liver tumor, we proceeded to emergency surgery based on the patient's clinical picture and the findings of a palpable abdominal mass. The exophytic growth of P-HCC usually tends to form a mass that expands into the surrounding organs, rather than infiltrating them.
The histological findings of this patient were very unusual, since P-HCCs are rare liver tumors and to our best knowledge there have been no reports in literature describing P-HCC combination to other tumors. The largest series dealing with the surgical results of pedunculated HCCs is reported by Yeh CN et al. [2], where no combination with other tumors has been observed.
According to their macroscopic appearance, P-HCCs are classified into pedunculated type with a pedicle (sub-type I, as is this case) and pedunculated type without a pedicle and attached to the liver surface (sub-type II) [3]. Horie et al. [5] have reported that almost all P-HCCs show poorly differentiated characteristics, using Edmondson and Steiner's classification [15]. Yeh et al. [2], in a large study of 18 hepatic pedunculated tumors from 432 patients with HCC, found that the P-HCC group with larger tumors (> 5 cm) had a significantly favorable overall survival (94 months), compared to lower survival (54.5 months) of the non P-HCC type II group. The pedunculated tumors tended to be larger and to have a more prominent capsule. Although increased tumor size is associated with poorer prognosis in HCC due to increased invasiveness, the patients with pedunculated tumors and pedicle have larger tumors but do not have a significantly decreased survival. Pedunculated tumors exhibit less vascular invasion than do non P-HCCs. Vascular invasion is widely accepted as the most consistently reported risk factor for recurrence after resection, which explains the improved survival seen in the P-HCC group of patients [2, 5, 16]. In our case, the presence of a long pedicle without vascular invasion made resection of the tumor easily controllable and allowed for gross disease clearance, which hopefully will lead to better prognosis and long-term survival.
