Primary B cell lymphomas of the skull base are uncommon and lack well-defined treatment guidelines. We report a case of diffuse, large B-cell lymphoma of the cavernous sinus with sphenoid sinus and clival extension, treated with partial resection, chemotherapy, and proton beam irradiation. To our knowledge, this is the first report of a skull-base lymphoma treated with protons. A 53-year-old female presented with a two-month history of diplopia, persistent headaches, and paresthesia over the left side of her mouth. A skull MRI revealed an enhancing mass in the right cavernous sinus and right sphenoid sinus. Transsphenoidal subtotal resection of the mass confirmed the presence of a diffuse, large B-cell lymphoma.

Treatment consisted of CHOP-R chemotherapy and locoregional radiation with protons. Locoregional radiation of the lesion required moderate doses, below the radiation tolerance of adjacent normal structures. Conformal protons were utilized to minimize the volume of normal brain receiving radiation. Conformal proton beam radiotherapy to a moderate dose proved valuable in this case because it minimized the volume of normal brain receiving low to moderate doses of radiation.

Key words: Lymphoma; Cavernous sinus; Clivus; Conformal; Proton; Radiation.