Background : Leiomyomas are benign tumors that exhibit various forms of smooth muscle differentiation from mesenchymal origin and the classic spindled form of leiomyoma is the most common pelvic tumor in females. However, primary hepatic leiomyoma (PHL) is a very rare tumor with a complex pathogenesis which remains largely unknown. In this case report, we describe a rare case of PHL in a middle-aged female who was asymptomatic with no history of hepatitis or other liver disease.

Methods : A 48-year-old female had revealed 7cm sized mass on liver segment 7 on abdominal ultrasound during annual health check-up. Liver dynamic CT and MRI were shown 8cm-sized arterial heterogeneously enhancing bilobular mass with gradual delayed central fill-in enhancement pattern in segment 7 and 1cm-sized another mass with same pattern in segment 8. She underwent regular follow-up every 6 months but the mass had to increase in size from 8cm to 11cm . Tumor markers including AFP, CA 19-9 and lab findings had shown within normal range and no history of viral hepatitis or no immunosuppressive medication use.

Results : The patient underwent S7 monosegmentectomy after 1 year from first diagnosed. The pathology had shown multiple leiomyoma with 7.5*4.2*4.0cm, 1.5*1.0*0.9cm with moderate hyperceullarity, mild nuclear pleomorphism. Mitoic count was below 1/10HPF and necrosis was not identified. Immunohistochemistry had shown positive smooth muscle actin but negative Dog-1, KIT, CD34, S100. She was discharged from hospital on postoperative 8th day without complication.

Conclusions : PHL is very rare tumor with complex pathogenesis which remains largely unknown. Imaging of the tumor does not allow for a tissue specific diagnosis. Surgical resection is both diagnostic and curative. The diagnosis of PHL should be considered as a differential in the management for live tumors.