Follicular Lymphoid Hyperplasia of the Infratemporal Fossa

A case report of a 33-year-old woman with an infratemporal mass consistent with benign follicular lymphoid hyperplasia is presented. The patient, who has a history of migraines and a long-standing seizure disorder, presented with complaints of intermittent left facial numbness, left eustachian tube dysfunction, and new-onset headaches distinct from previous migraines. Interval MRI scans over 6 months showed an increase in size of an enhancing, heterogeneously shaped mass of the left infratemporal fossa—isointense to brain parenchyma on T2 and hyperintense on FLAIR, without extension into the cranial vault. Based on the infratemporal location of the lesion, diagnoses considered included schwannoma, paraganglioma, neurofibroma, hemangioma, meningioma, lymphoma, and sarcoma. We obtained further imaging to evaluate the lesion. Computed tomography (CT) imaging demonstrated the lesion abutting the orbital and maxillary sinus walls with some extension into the nasal cavity, left maxillary sinus, left sphenoid sinus, and ethmoid sinuses. Angiographic imaging indicated no evidence of aneurysm, vascular malformation, or large vessel occlusion. Transantral, transmaxillary endoscopic biopsy of the lesion was obtained. Initial frozen section pathology identified a small round blue cell infiltrate. Because of the infiltrate, flow cytometry was performed. Pathological evaluation of the specimen, which considered processes suggested by the patient's age, location and radiographic appearance of lesion, and frozen section reading, included lymphoma, small cell carcinoma, lymphoepithelioma, various sarcomas, and pseudolymphoma. The final pathological diagnosis revealed the lesion to be follicular-patterned lymphoid hyperplasia. This case represents a unique incidence of lymphoid hyperplasia in the infratemporal fossa. The diagnostic challenges presented by this case will be discussed in detail.