Primary Exophytic Extraskeletal Osteosarcoma of the Liver: A Case Report and Literature Review

INTRODUCTION: Primary hepatic extraskeletal osteosarcoma (ESOS) is a rare tumor with no specific clinical manifestations, and little is known about it. Here, we describe an elderly patient with primary hepatic osteosarcoma confirmed by pathology results to raise awareness. CASE REPORT: We report an unusual case of a 62-year-old man who presented with right upper quadrant pain. The inflammatory indicators were elevated, and alkaline phosphatase (AKP), carbohydrate antigen (CA-199 and CA-125) were slightly increased. Computed tomography images and magnetic resonance images discovered a 7.8 × 7.4 × 6.6 cm mass with irregular radiated and cotton-like tumor bone between the liver and right kidney space. Pathology revealed the mass to be primary exophytic ESOS of the liver. The patient underwent a surgical operation and standard chemotherapy and is still alive with no recurrence and metastasis to date. CONCLUSION: Owing to the rarity of the tumor and the lack of clinical characteristics and specific laboratory indexes, it is difficult to make a correct diagnosis. Medical imaging features mainly behave soft tissue entity with tumor bone composition. Surgical resection combined with adjuvant chemotherapy is the main treatment for ESOS.