Intramedullary spinal cord metastasis following spontaneous malignant transformation from giant cell tumor of bone 16 years after pulmonary metastasis

Giant cell tumor (GCT) of the bone is a unique bone tumor that can behave in locally aggressive fashion despite its benign histological appearance, and the local recurrence rate is approximately 25-35% following curettage, supplemented with bone grafting, cementation, cryosurgery, or instillation of phenol or ethanol [1, 2]. Pulmonary metastases, or so-called pulmonary implants, are also a well-documented phenomenon in conventional GCT of the bone, with an incidence of from 1 to 9% of patients with GCT in the literature [3-7]. They have generally self-limited growth potential and a relatively good prognosis; thus, surgical resection of pulmonary metastatic lesions as much as feasible is the treatment of choice. However, approximately 25% of patients with unresectable metastasis eventually die of the disease [1]. Much more unusually, GCT of the bone can metastasize to extrapulmonary sites, including the bone (actually indistinguishable from multicentric GCT of the bone), scalp, prepuce, brain, and mediastinal and regional lymph nodes, especially in the presence of simultaneous pulmonary metastatic lesions [8, 9]. However, intramedullary spinal cord metastasis is an extremely rare event, even in cases of malignant tumors, such as lung and breast cancers [10, 11]. As far as we know, there have been no reports documenting intramedullary spinal cord metastasis from GCT of the bone with or without malignant transformation. The present report describes a patient presenting with an intramedullary spinal cord metastasis following spontaneous malignant transformation from conventional GCT of the bone 16 years after pulmonary metastasis. The patient was informed that data from the case would be submitted for publication and gave her consent during her lifetime.