Abstract
Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma accounting for approximately one-third of all cases. DLBCL can present as a lymph node or extranodal tumor. Cavernous sinus (CS) is a small but complex structure in which various arteries, sympathetic plexuses, and cranial nerves are passing through. Cavernous sinus syndrome (CSS) results from any disease process that affects CS including tumor, vascular disease, infection, or inflammation. Herein, we report a case of extranodal DLBCL diagnosed by skin biopsy presenting as CSS. A 58-year-old male presented with a 3-week-old, gradually growing subcutaneous nodule on the left upper lip. He also suffered from ptosis, ophthalmoplegia, diplopia, and headache confined to the right side for 3 months. Histopathologic examination of the left upper lip showed dense dermal infiltration of atypical large tumor cells resembling centroblasts and immunoblasts. Immunohistochemistry studies revealed that the tumor cells were positive for CD20, BCL2, BCL6, MUM1, and MYC. After additional radiologic evaluation with positron emission tomography-computed tomography (PET-CT), brain magnetic resonance imaging, and orbital CT, he was finally diagnosed with extranodal DLBCL involving the right CS, oculomotor muscles, and left upper lip.