Giant-cell neoplasm of the sphenoid sinus.

A rapidly growing giant-cell neoplasm arising in the sphenoid sinus of a 26-year-old man is reported. The patient's only initial symptoms were severe headaches and left sixth-nerve palsy. Computerized tomography of the brain showed extensive tumor infiltration of the bony structures and soft tissues of the base of the skull. A transsphenoidal surgical procedure proved unsuccessful in removing the tumor. Histologic examination revealed a proliferation of osteoclast-type giant cells against a background of highly atypical mononuclear cells, raising the question of malignancy. The differential diagnosis and problems in nomenclature of this lesion are discussed.