Primary liver carcinoma with sarcomatous change is a rare malignancy associated with high aggressiveness and poor prognosis. However, the characteristics of these types of tumors are still unknown. The aim of this study was to assess the imaging features, prognostic significance, and clinicopathological characteristics of patients with these tumors. Of 1070 patients who underwent surgical resection of primary liver carcinoma at Toranomon Hospital (Tokyo, Japan) from 2003 to 2017, 10 patients were diagnosed with primary liver carcinoma containing sarcomatous component. This study included all 10 patients. We evaluated the percentage of the sarcomatous component in each tumor. Patients were classified into two groups: the low percentage group (area of sarcomatous changes ≤30%) and high percentage group (area sarcomatous component ≥70%). We also divided patients into two groups based on the combination of the percentage of sarcomatous tissue and tumor size (≥40 mm or <40 mm). The overall survival rate of patients with ≥70% sarcomatous component and ≥40 mm tumor was significantly worse than that of patients with ≤30% sarcomatous tissue or <40 mm tumor size (P = 0.0059). The results confirmed the poor prognosis of patients with sarcomatous changes in primary liver carcinoma, especially those with large sarcomatous component and large tumor size. Radical resection in the early stage is recommended to improve prognosis.