2024 Volume 33 Issue 8 Pages 550-555
Schwannomas are generally benign tumors derived from Schwann cells of the peripheral nerves, most commonly the eighth cranial nerve. Anterior skull base schwannomas account for less than 1% of all intracranial schwannomas, and pre-operative diagnosis is difficult due to the lack of characteristic imaging findings. Here, we report a case of an anterior skull base tumor that was difficult to diagnose pre-operatively but was diagnosed as a schwannoma on histopathological examination.
A 51-year-old man presented with headache and lightheadedness. At the time of the initial medical examination, the patient had a Japan Coma Scale score of 1, and decreased bilateral sense of smell, cognitive function, attention span, and activity. Head computed tomography showed bone destruction and intratumoral hemorrhage, and gadolinium-enhanced T1-weighted magnetic resonance imaging showed a heterogeneous contrast effect. Pathological examination confirmed a schwannoma. The patient was transferred to a convalescent rehabilitation hospital on the 32nd post-operative day.
Most frontal skull base schwannomas are extramedullary intradural tumors that cause bone thinning without destruction of the frontal skull base bone. In the present case, cribriform plate bone destruction and extension into the paranasal sinus was observed, which is atypical for anterior skull base schwannomas. Angiographic findings suggestive of malignancy, such as tumor staining, also contributed to the difficulty in diagnosis. Although rare, schwannomas should be included in the differential diagnosis in cases of anterior skull base tumor.
