Hepatocellular Carcinoma (HCC): This is the most common primary liver cancer, especially in patients with risk factors such as hepatitis B or C infection, alcohol use, or cirrhosis. A tumor size of 5.8 cm is consistent with HCC, which can present as a single large mass.

Metastatic Liver Disease: Given the size of the tumor, metastasis from another primary cancer (e.g., colorectal, breast, lung) is a strong consideration, especially if the patient has a known history of cancer.
Hemangioma: Although typically benign and smaller, large hemangiomas can present similarly to malignant tumors. However, they are less likely to be this large and symptomatic.
Focal Nodular Hyperplasia (FNH): A benign tumor of the liver, though less common and usually smaller than 5 cm.

Intrahepatic Cholangiocarcinoma: A malignancy of the bile ducts within the liver, which can present as a large mass. Missing this diagnosis could lead to delayed treatment and poor outcomes.
Liver Abscess: Although typically presenting with significant symptoms like fever and pain, a large liver abscess could be mistaken for a tumor. This condition requires urgent drainage and antibiotic treatment.
Hepatic Adenoma: Benign but can rupture and cause severe bleeding. Important to consider, especially in young women with a history of oral contraceptive use.

Hepatoblastoma: A rare malignant liver tumor, mostly occurring in children.
Angiosarcoma of the Liver: A rare and aggressive tumor originating from the blood vessels of the liver, often associated with exposure to certain chemicals like vinyl chloride.
Epithelioid Hemangioendothelioma: A rare, malignant tumor of the liver with a variable prognosis.
Primary Liver Lymphoma: Extremely rare and usually associated with immunosuppression or chronic inflammation.