Presentation
Headache, nausea, vomiting and facial pain for 4 months. No fever or history of trauma
Patient Data
A large heterogeneously enhancing mass with intralesional and peripheral hypodense cystic components. The mass has local mass effect with associated subfalcine herniation, effacement of ipsilateral lateral ventricle and early contralateral entrapment hydrocephalus. The mass is centered over the skull base with the smooth bone remodeling and expansion of Meckel's cave.
MRI confirms an extra-axial mass with CSF cleft centered over porus trigeminus. The mass is T2W and FLAIR hyperintense signal, demonstrating facilitated diffusion and intra-lesional blooming artifact on SWI. The avidly enhancing mass has non-enhancing peripheral cysts. No associated dural tail. The internal carotid artery abuts the mass and is displaced medially.
Histopathology:
Macroscopy:
Specimen consists of multiple fragments of tissue, the largest measuring 40 x 20 x 15 mm.
Microscopy:
Sections show multiple tissue fragments demonstrating a tumor composed of hypercellular areas( Antoni A) and a myxoid pauci-cellular (Antoni B). The cells are spindle-shaped, with tapered nuclear ends and eosinophilic cytoplasm. Nuclear palisading around fibrillary processes (Verocay bodies) is often seen. Scattered mast cells and blood vessels are seen. Isolated large cells with hyperchromatic nuclei are noted. There is no evidence of malignancy.
Immunohistochemistry:
s100: diffusely positive
Pathologic diagnosis consistent with schwannoma
Case Discussion
The imaging finding demonstrates a large heterogeneously enhancing mass with cystic components and remodeling of porus trigeminus. Differential includes meningioma, metastasis, chondrosarcoma and vestibular schwannoma. The patient subsequently underwent surgical resection with pathology confirming a trigeminal schwannoma.