Granular cell tumors of the neurohypophysis with atypical imaging features: a case report and literature review

Granular cell tumors (GCTs) of neurohypophysis are rare, the incidence rate of GCTs is higher in female patients compared to male patients, the enlarged GCTs in neurohypophysis can compress the optic chiasm and cause changes in the patient’s visual acuity and visual field. Complete surgical resection is often regarded as the best treatment and can be accomplished via either endoscopic transsphenoidal or open microsurgical approaches, depending on the configuration and topography of the lesion. We report a case of a tumor originating from the pituitary gland with visual field defect as the initial symptom, and with atypical imaging features. A 62-year-old female had visual field defect in eyes and symptoms of dizziness. The brain imaging examination revealed a mixed signal quasi-circular tumor in the suprasellar region, the initial imaging diagnosis was craniopharyngioma. Tumor resection surgery was determined to be appropriate. During the operation, we found that the tumor was located behind and below the optic chiasm and compressed the optic chiasm. The tumor was completely resected during the operation and the postoperative pathological results suggested that it was the neurohypophysis granular cell tumor. The patient recovered well after surgery without complications such as diabetes insipidus, electrolyte disorders, or high fever. The visual field was also improved. The three months follow-up MRI of the head showed no recurrence. GCTs of the neurohypophysis are rare tumors that should be included in differential diagnosis when suprasellar tumors are detected. Surgical resection is an effective treatment option. However, it is important to be aware of complications such as pituitary associated with surgeries. The further imaging characteristics of GCTs still require large-scale clinical research.