Mixed Pituitary Gangliocytoma and Prolactinoma Resistant to the Cabergoline Treatment.

Background: A gangliocytoma rarely coexists with a pituitary adenoma in a sellar lesion. Herein, we describe our experience in treating a mixed gangliocytoma and prolactinoma of the pituitary gland.

Case Description: A 16-year-old male presented with severe headache and vomiting. Magnetic resonance imaging showed a large pituitary tumor with hydrocephalus. Because of the increased levels of serum prolactin (PRL), we treated the patient with cabergoline, which decreased the tumor size and improved the hydrocephalus. Six months after the treatment, the tumor began to increase in size, despite the normalization of the PRL level with cabergoline treatment. An endoscopic transsphenoidal resection was performed and the tumor was mostly removed. Microscopic examination of the resected tumor showed a mixture of prototypical pituitary adenoma cells and the proliferation of mature ganglion cells. Immunohistochemistry showed that the ganglion cells were positively stained for synaptophysin, NeuN, and PRL as shown in the adenomatous component. A few cells were immunostained with both PRL and NeuN, and a few cells were immunopositive for nestin, but not PRL or synaptophysin.

Conclusions: Our findings showed the existence of cells that are phenotypically intermediate between ganglion cells and adenoma cells, and the existence of stem cell-like cells, which support the hypothesis that adenoma cells can transform into ganglion cells or that both ganglion and adenoma cells derive from common stem cells. Furthermore, the ganglion cells seemed to grow rapidly and independently of dopamine, which is in contrast to prototypical prolactinoma cells.