2025 Poster Presentations
P032: OLFACTORY GROOVE TUMORS: DIFFERENTIATING SCHWANNOMA FROM MENINGIOMA IN A COMPLEX CASE
Maxwell A Marino, DO, MPH1; Ali O Jamshidi, MD2; Fernando A Torres, MD3; 1Riverside University Health System, Moreno Valley; 2Kaiser Permanente Medical Center, Woodland Hills; 3Kaiser Permanente Medical Center, Los Angeles
Olfactory groove Schwannomas (OGS) are exceedingly rare and often misdiagnosed preoperatively due to their radiological resemblance to more common olfactory groove meningiomas. This case presents a 38-year-old male with a history of endoscopic transnasal, transsphenoidal resection for a presumed olfactory groove meningioma, which was later histologically confirmed to be an olfactory nerve Schwannoma. This report aims to review the literature on the typical presentation and imaging characteristics of these tumors and discuss the challenges in differentiating them radiographically. The case also proposes potential imaging features that may aid in distinguishing these two entities preoperatively.
The patient, initially presenting with headaches and a presumed diagnosis of radiation-induced meningioma, underwent an endonasal resection of an anterior cranial fossa mass. Imaging prior to surgery favored the diagnosis of a meningioma based on characteristic findings, including a well-defined extra-axial mass with dural attachment, a hallmark of meningiomas. However, postoperative histopathology revealed the mass to be a Schwannoma, confirmed through immunohistochemical markers including S100 positivity and SOX10.
Imaging features of meningiomas typically include homogenous enhancement, dural tail sign, and hyperostosis. In contrast, Schwannomas may present with more heterogeneous enhancement, cystic degeneration, and involvement of cranial nerves. Despite these general distinctions, significant overlap exists, leading to diagnostic challenges, as evidenced by this case. A key learning point from this case is that the radiological appearance alone may not always be reliable in distinguishing between these two tumors. Neuroradiologists might maintain a high index of suspicion for Schwannomas, especially when imaging features suggest cranial nerve involvement or heterogeneity within the tumor mass. Furthermore, outcomes related to olfaction could more reliably be predicted if imaging characteristics could suggest the diagnosis of a schwannoma.
This case highlights the diagnostic challenges posed by olfactory groove Schwannomas mimicking meningiomas and underscores the need for careful radiological and clinical evaluation. Future research should aim to refine imaging protocols to better differentiate these entities and avoid misdiagnosis, ultimately improving preoperative planning and patient outcomes.