BACKGROUND: Hepatic cavernous hemangioma (CH) is the most common hepatic benign tumor. Most cases are solitary, asymptomatic, and found incidentally. In symptomatic cases with rapidly growing tumors and coagulopathy, surgical treatment is considered. In rare cases, diffuse hepatic hemangiomatosis (DHH) is reported as a comorbidity. The etiology of DHH is unknown. CASE PRESENTATION: A 29-year-old female patient had a history of endometriosis treated with oral contraceptives. Hepatic CH was incidentally detected in the segment IVa of the liver according to the Couinaud classification. Follow-up computed tomography (CT) and ultrasound sonography showed the growth of the lesion and formation of multiple new lesions near the first. Enhanced CT and magnetic resonance imaging (MRI) revealed that the new lesions were different from CH. Although oral contraceptives were stopped, all lesions grew in size. Malignancy and possibility of rupture of these tumors were considered due to the clinical course, and we opted for surgical removal of the tumors. Left liver lobectomy and cholecystectomy were performed. Surgical findings were small red spot spreading and a mass in segment IV of the liver. Pathological examination revealed a circumscribed sponge-like tumor with diffuse irregular extension to the adjacent area. Both of the lesions consisted of blood-filled dilated vascular spaces lined by flat endothelium without atypia. The diagnosis was hepatic CH with DHH. The patient was discharged on postoperative day 12 uneventfully. CONCLUSION: We report the successful resection of CH with DHH. The case findings suggest a relationship between oral contraceptive use and enlargement of CH and DHH. Although DHH has been poorly understood, a few previously published cases reported DHH occurrence in patients using oral contraceptives. In such cases, the decision to perform surgical resection should be made after careful examination.