A Rare Case of Intravascular Large B-cell Lymphoma Presenting With Bilateral Ophthalmoplegia, Along With a Literature Review.

Intravascular large B-cell lymphoma (IVLBCL) is a subtype of extranodal lymphoma that characteristically contains malignant lymphocytes within blood vessels. The clinical presentation of IVLBCL has high variability. In our case, the patient's initial presentation involved bilateral ptosis, restricted extraocular movements, periorbital pain, and bitemporal headache. The patient denied the classic "B symptoms" such as fever, night sweats, or weight loss. The patient also denied a family history of malignancy. Initial imaging studies were unremarkable, making diagnosis particularly challenging. Ultimately, functional endoscopic sinus surgery was performed. Pathological examination of the intraoperative specimen revealed a CD5+ large B-cell lymphoma within the vessels involving the left ethmoid sinus, respiratory mucosa, and nasal septum. The patient underwent steroid therapy prior to diagnosis, which led to rapid improvement in headache and mild improvement in extraocular function and ptosis. Following diagnosis, the patient underwent chemotherapy with supportive medications. Our case report may be considered a reference for cases presenting with extensive bilateral extraocular muscle deficits and levator palpebrae dysfunction in the absence of notable initial imaging findings, "B symptoms," or positive family history. The teaching point from this case is to demonstrate the difficulty of diagnosis and our train of thought in investigating an abnormal presentation with no clearly identifiable etiology following initial diagnostic workup and treatment.