Clinical History
A 23-year-old woman was admitted due to abdominal fullness, right upper quadrant pain and fever of one month’s duration. Physical examination revealed hepatomegaly and liver tenderness. Laboratory tests showed leukocytosis and elevated serum transaminases. AFP and CEA were within normal limits and HBsAg was negative.
Imaging Findings
MDCT of the abdomen revealed severe hepatomegaly. Unenhanced scanning demonstrated a large, ill demarcated heterogeneously hypodense mass in the right lobe of the liver (Fig. 1). Contrast enhanced CT at arterial phase revealed rapid, early, marked enhancement in the periphery of the mass and an abundance of large, tortuous blood vessels surrounding the tumour (Fig. 2). At portal and delayed phases mild contrast enhancement of the solid components of the mass was noted (Fig. 3, 4). Large hypodense parts within the tumour corresponded to areas of necrosis on histopathology. A small amount of ascites was present. No evidence of portal vein invasion, bile duct obstruction or regional lymph node metastasis was detected.
Clinical history and CT imaging features of a large necrotic mass were strongly suggestive of a hepatic sarcoma.
Histology following an extended right hepatectomy reported the presence of primary malignant fibrous histiocytoma of the liver, of the inflammatory variety.
Discussion
Background
Malignant fibrous histiocytoma (MFH) is the most common soft tissue sarcoma. It is considered to originate from undifferentiated primitive mesenchymal cells and has five different histological subtypes: storiform pleomorphic, myxoid, giant cells, inflammatory, and angiomatoid. It is a relatively rare tumour, however, it is the commonest sarcoma arising in adult population (6th-7th decades) with a slight male predominance. It may occur in any part of the body and most commonly in the extremities (lower extremity 49%, upper extremity 19%), followed by the retroperitoneum (16%) and peritoneal cavity (5-10%) [1-6].
Liver is an exceptional site of involvement, with no predilection for one lobe. The prognosis is poor, with a 2-year survival rate of approximately 60% [4-6]. This is a case of primary MFH of the liver presenting in a young woman.
Imaging perspective
The CT findings of primary MFH of the liver are closely correlated with the histopathologic characteristics and the size of the lesion. At unenhanced CT, it usually appears as an ill-defined or a well circumscribed large or multinodular mass, heterogeneously hypodense, owing to the presence of necrosis. Occasionally, intratumoural calcifications have been reported [1-3].
Following contrast material injection, various enhancement patterns may be noted. A strongly and heterogeneously enhancing mass with several necrotic areas is usually seen. An abundance of blood vessels surrounding the tumour has also been reported and this was seen in our patient. This pattern is mainly correlated with the inflammatory variety of MFH [1, 2]. CT findings also include the presence of a contrast-enhancing pseudocapsule surrounding the lesion or a multilocular cystic mass with fibrous septa enhancement. Solid components and fibrous septa may better enhance on delayed scanning, depending on the amount of fibrosis. Small lesions may appear solid and homogeneously enhancing. Cong et al. reported the CT findings in five patients with MFH of the liver as a ‘fast rushing in and washing out’ enhancement pattern, probably due to the presence of less fibrous tissue in these tumours [2].
MFH may involve the liver capsule and adjacent organs, but without evidence of portal vein invasion, bile duct obstruction, or regional lymph node metastases.
Although there are no specific imaging findings of liver MFH it should be included in the differential diagnosis in a patient with a large necrotic mass with rapid growth combined with an aggressive clinical course, as in this case [1-6].
Differential Diagnosis List
Primary malignant fibrous histiocytoma of the liver
Hepatic adenoma
Haemangioma
Hepatocellular carcinoma (HCC)
Fibrolamellar HCC
Cholangiocarcinoma
Hepatic epithelioid haemangioendothelioma
Undifferentiated embryonal sarcoma
Final Diagnosis
Primary malignant fibrous histiocytoma of the liver
