H epatocellular carcinoma (HCC) is responsible for high incidence of cancer-related mortality worldwide (1, 2). Diagnosis of HCC is a well-known topic, and now it can be made solely by imaging findings in cirrhosis (3,4). Advances in imaging procedures and intense follow-up of high-risk patients led to increased early detection of HCC and better treatment options (5, 6). However, even in good surgical candidates, long-term survival rates remain unsatisfactory because of high recurrence (7,8). Presence of microvascular invasion (MVI) has been reported to be one of the most important risk factors related to postsurgery tumor recurrence (9-11). Presence of MVI alters the surgical procedure. MVI is a prognostic factor associated with lower survival and higher recurrence rates. Prediction of MVI may also affect locoregional treatments along with chemotherapy protocols. This review will focus on all aspects of MVI.
The effect of microvascular invasion on survivalEarly tumor recurrence is linked to increased mortality rate. Lim et al. (9) reported that MVI is a more prominent tumor recurrence predictor than the Milan criteria for HCC after surgical resection. The patients who fulfill the Milan criteria should have a solitary tumor not exceeding 5 cm or three or fewer tumors with the largest not exceeding 3 cm, and no evidence of macrovascular invasion or extrahepatic metastasis (5, 9). Lim et al. (9) concluded that patients (without MVI) exceeding the Milan criteria could achieve comparable overall survival rates after surgical resection, relative to patients within the Milan criteria. However, overall survival decreased significantly with MVI, independently of the Milan criteria.In a different study, authors grouped the patients into mild (one to five invaded vessels) and severe (more than five invaded vessels) MVI groups (5). They found that the three-year recurrence-free survival rates for patients with and without MVI were 27.7% and 62.5%, respectively. They also reported that recurrence-free survival rates at two years for patients without MVI, with mild MVI, and severe MVI were 75.9%, 47.2%, and 32.7%, respectively (5). Goh et al. (12) studied patients who had surgical resection of multifocal HCC and revealed that the presence of MVI and the number of nodules (which is also a result of MVI) were more important prognostic factors than tumor size (12). They also suggested that the current American Joint Committee for Cancer TNM staging system, which uses tumor size, but not MVI, as prognostic criteria for multifocal HCC, needs to be revised (12).
The indicators of microvascular invasionDespite its significance in HCC assessment, MVI can rarely be diagnosed preoperatively. However, the presence of MVI may be predicted by key radiologic findings and specific lab- We reviewed the literature and aimed to draw attention to clinicopathologic and imaging findings that may predict the presence of microvascular invasion in hepatocellular carcinoma. Imaging findings suggesting microvascular invasion are disruption of capsule...