Sellar Schwannoma Masquerading as Giant Pituitary Adenoma: A Diagnostic Challenge.

Background: Schwannomas are well-encapsulated, solitary tumors that grow slowly from the nerve sheath. Sellar schwannomas tend to be mistaken for other sellar/parasellar lesions due to similar clinical and radiological findings. The present article describes the clinical presentation, radiological findings, histopathological features, and outcome of a patient with sellar schwannoma. Case Description: A 23-year-old female, known to have hypothyroidism secondary to Hashimoto's thyroiditis, presented with multiple episodes of galactorrhea, weight gain, and irregular menstrual cycle for 8 months. It was associated with decreased visual acuity and episodic headaches. Neurological examination revealed no focal deficits. Brain magnetic resonance imaging (MRI) showed a well-defined lobulated lesion in the sellar region, compressing the right optic nerve and optic chiasm. The patient underwent craniotomy and tumor resection. The histopathological sections were diagnostic of schwannoma. Postoperatively, the patient noted a subjective improvement in her visual acuity. She was discharged in stable condition with regular follow-ups at neurosurgery, endocrine, and ophthalmology clinics. Conclusion: Schwannoma of the sellar region is rare and can be misdiagnosed as pituitary adenomas. Preoperative hormonal profile and meticulous neuroradiological assessment narrow down the differential diagnosis for patients with sellar lesions. The diagnosis of sellar schwannomas is established with histopathology and immunohistochemistry results.