Giant cell tumor of the sphenoid bone: a systematic literature review with illustrative cases.

Giant cell tumors of the bone (GCT) are typically benign but locally aggressive tumors usually affecting the long bones of young adults. Rarely, these tumors may arise in the skull, most often involving the sphenoid or temporal bones. Here, we performed a systematic literature review and identified 79 previously reported cases of GCT of the sphenoidal bone, and we added add two illustrative cases of patients affected by this condition. The first patient, a 22-year-old woman, was treated with surgery and radiotherapy and has been followed for 17 years without evidence of tumor recurrence. The second patient was seen recently and was treated with two successive surgeries. These tumors usually occur between the second and the third decade of life and are more prevalent in women. Symptoms leading to diagnosis are related to local mass effect and include headache, third and sixth cranial nerve palsy, impaired facial sensitivity, diplopia, and decreased vision, and clinical manifestations of endocrine dysfunction may also be present. Imaging techniques usually depict an osteolytic lesion of the sphenoid bone extending to adjacent anatomical structures. Differential diagnoses include invasive pituitary adenomas, chordomas, chondrosarcomas, brown tumors, and giant-cell reparative granulomas. The diagnosis is confirmed histologically, characterized by numerous osteoclast-like multinucleated giant cells, mononuclear cells, and stromal cells, the latter showing histone H3 G34W/R/V mutations on immunohistochemistry. Transsphenoidal surgery remains the first-line treatment, while radiotherapy or denosumab may be considered in cases of residual, progressive, or recurrent disease.