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Giant pedunculated hepatocellular carcinoma masquerading as a pelvic mass: a case report

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world, with high frequency rates in Asia. Many of the patients have unresectable disease at the time of diagnosis, and early detection and surgical resection is the best hope for survival. But, if HCC is presenting as an extrahepatic mass, the diagnosis is difficult. Herein, we report a case of primary HCC masquerading as a pelvic mass. A 74-year-old woman was admitted to our hospital due to a palpable mass in the lower abdomen. CT scan detected an approximately 15.0×13.4×11.4 cm-sized multilobulated homogeneous enhancing mass in the right adnexa. Operative findings showed that the pelvic mass originated from the liver. We performed hepatic wedge resection. Permanent histopathologic report revealed primary HCC. Exophytic-growing hepatocellular carcinoma should be carefully diagnosed.


INTRODUCTION
Hepatocellular carcinoma (HCC) is a hyperendemic disease in Korea. Age-adjusted incidence was 24.5 per 100,000 population and 40.2 per year in males according to the Central Cancer Registry in Korea. 1 The incidence is high compared to that in other countries. Mortality rate of HCC is second to that of lung cancer in males, and it is the fourth highest among females in Korea. 1 But, pedunculated HCC (P-HCC) is a very unusual form of HCC.
Horie et al. reported an incidence of P-HCC of 0.24-3.0% among all HCCs in Japan. 2 Other abdominal tumors mimic P-HCC, and therefore, differential diagnosis is usually very difficult. In addition, diagnosis is delayed due to nonspecific symptoms and clinical features. Therefore, the resection rate of P-HCC is high, but the prognosis is poor due to recurrence and metastasis to the peritoneum, adrenal glands, and spleen. [3][4][5] In our case also, it was difficult to diagnose P-HCC because it was mistaken for a pelvic mass. We describe a case of primary HCC that was detected incidentally during an obstetric operation. were negative. Also, tumor markers such as alpha-fetoprotein (AFP), cancer antigen (CA)-125, CA19-9, β-hCG   (Fig. 1).

CASE
Hence, the initial impression was of a huge myoma uteri or right adnexal mass such as germ cell tumor (e.g. dysgerminoma, choriocarcinoma). Thus total abdominal hys-terectomy with bilateral salpingo-oophorectomy was planned in the gynecologic department. During the operation, an exophytic mass with a thin peduncle originating from the left lateral hepatic lobe was observed. The mass was not infiltrating the uterus, the ovary and the other organs.
Frozen-section biopsy was performed. The biopsy result was adenoma of uncertain origin, but carcinoma could not be excluded. Grossly, the tumor was fairly well-circumscribed and encapsulated. Remnant liver looked normal in color and consistency (Fig. 2). Therefore, we performed wedge resection of the hepatic mass leaving an adequate On pathologic examination, the mass was a 15×15 cm-sized nodular type, and the Edmondson and Steiner's histologic grade was III. Capsular invasion was present, but the other findings including vascular invasion were absent (Fig. 3).

DISCUSSION
Eggel classified the gross type of HCC into three types: nodular, diffuse, and massive. 6 P-HCC is of the nodular type with exophytic growth. It was first described by Roux in 1897 as a carcinoma that protrudes from the liver with or without a pedicle. 7 The first case of P-HCC was reported by Goldberg and Wallenstein in 1934, which showed a 1.5 cm-sized pedicle and it originated in the left inferior hepatic lobe. 8 The incidence of P-HCC was reported to be 0.24%-3.0% of all HCCs in Japan. 2 Of 432 surgical resected hepatocellular carcinomas, 18 (4.2%) were P-HCCs in a Taiwanese study, and the male to female ratio was 2:1 with a mean age of 47.8 years. 9 According to their gross appearance, P-HCCs can be classified into pedunculated type with a pedicle as in our case, and pendunculated type without a pedicle and attached to the liver surface. 10,11 The etiology of P-HCC is not clear. Mainly, P-HCC was mostly detected in the accessory lobe of the liver, and the accessory lobe is usually located on the right inferior hepatic lobe; however it can be located on the other lobe. 12  It is also misdiagnosed as a splenic or peritoneal mass. 3,4 Similarly, it may invade the duodenum and mimic a duodenal gastrointestinal stromal tumor. 15 Although the imaging modalities (CT and MRI) have improved, it is still difficult for a radiologist to determine the tumor origin. It can be misdiagnosed due to its location, and adherence to other organs. In our case, preoperative diagnosis was a right adnexal mass such as germ cell tumor or myoma uteri, but at the time operation, the mass was found to originate from the liver. Also, the laboratory findings were nonspecific. In a Japanese study, the positive rate of AFP, which is generally used as a tool for differential diagnosis between HCC and other abdominal tumors, was reported to be 68% in HCC and 66% in P-HCC, and there was no significant difference. 16  It has been reported that the prognosis is related to tumor size, capsular invasion, resection margin, and vascular invasion. 9, 18 Horie et al. 19 reported that almost all P-HCCs show poorly differentiated characteristics using the Edmondson and Steiner's classification. 20  with a large P-HCC (＞5 cm) is better than the overall survival (54.5 months) of patients with non P-HCC type II. Especially, vascular invasion has been known to be associated with prognosis and recurrence of HCC. 18 Vascular invasion is relatively low in the P-HCC type. 13 In our case also, vascular invasion was not observed.
In conclusion, although the imaging modalities have improved, it is difficult to diagnose P-HCC due to its ambiguous origin. But if there is no vascular invasion, the prognosis is better than that in the other types. Also, it is easier to perform surgical resection of the P-HCC type than the other types. Therefore whenever possible, active treatment including surgical resection should be performed.