Malignant transformation of a recurrent giant cell tumor of bone with lung metastasis: a case report

Abstract

Giant cell tumors (GCT) are benign tumors with potential for aggressive behaviour and capacity to metastasize. It is a locally destructive tumor that occurs predominantly in long bones of adolescents and young adults in the epiphysis. Although rarely lethal, benign bone tumors may be associated with a substantial disturbance of the local bony architecture that can be particularly troublesome in peri-articular locations. It is characterized by a proliferation of mononuclear stromal cells and the presence of many multi-nucleated giant cells with homogenous distribution. There are varying surgical techniques ranging from intra-lesional curettage to wide resection. As most giant cell tumors are benign and are located near a joint in young adults, several authors favour an intralesional approach that preserves anatomy of bone. Although GCT is classified as a benign lesion, few patients develop progressive lung metastases with poor outcomes. Malignant transformation without radiotherapy exposure, is an uncommon event, occurring in less than 1% of giant cell tumors of bone. Here we reported a case of recurrent GCT of tibia that at the time of final recurrence was found to have undergone malignant transformation over a period of 6 years following several limb salvaging procedures. Concurrent metastases were found in the lung, but these were non-transformed GCT following which the patient has undergone above knee amputation.