10242- ML-11 A CASE OF PRIMARY CAVERNOUS SINUS MALIGNANT LYMPHOMA DIAGNOSED BY CRANIAL BIOPSY

Abstract BACKGROUND AND AIMS Following neuroimaging studies, stereotactic irradiation is frequently utilized to treat cavernous sinus tumors. However, differentiating these tumors presents a significant challenge due to the overlapping imaging characteristics of various benign and malignant conditions, including cavernous hemangiomas, pituitary adenomas, schwannomas, meningiomas, sarcoidosis, and metastatic brain tumors. PATIENT PRESENTATION We report a rare case of diffuse large B-cell lymphoma (DLBCL) diagnosed via cranial biopsy of a cavernous sinus tumor. A 57-year-old man presented with a one-month history of diplopia and right-sided facial discomfort. Physical examination revealed right abducens nerve palsy and hypoesthesia in the distribution of the second branch of the right trigeminal nerve. Gadolinium-enhanced magnetic resonance imaging (MRI) demonstrated a homogeneously enhancing mass extending from the right cavernous sinus to the ipsilateral optic nerve canal, Meckel’s space, and foramen ovale. Whole-body computed tomography (CT) revealed no abnormalities. A cranial tumor biopsy was performed via an extradural temporopolar approach, resulting in a histopathological diagnosis of DLBCL. TREATMENT AND RESULTS Postoperatively, the patient underwent treatment with R-MPV (rituximab, methotrexate, vincristine, and procarbazine), pola-R-CHP (polatuzumab vedotin, rituximab, cyclophosphamide, doxorubicin, and prednisolone), and methotrexate infusion. Two months post-treatment, MRI revealed a reduction in the mass lesion, accompanied by improvements in both diplopia and trigeminal neuralgia. INTERPRETATION Primary malignant lymphoma of the cavernous sinus is characterized by a poor prognosis, with overall survival typically limited to a few months. Patients commonly present with facial pain and ocular motility disturbances. The lack of distinctive imaging findings complicates preoperative diagnosis. Although rare, primary malignant lymphomas should be included in the differential diagnosis of cavernous sinus tumors. Accurate histopathological diagnosis of these tumors is crucial for determining appropriate treatment regimens.