Pituicytoma with Significant Tumor Vascularity Mimicking Pituitary Macroadenoma

Abstract

A 19-year-old man presented with bitemporal hemianopsia and was found to have a large sellar and suprasellar tumor, resembling a pituitary macroadenoma. Emergency transsphenoidal approach was attempted because of rapid visual deterioration with headache. However, the approach was complicated and stopped by uncontrolled hemorrhage from the tumor. After conventional cerebral angiography and recognition of an unusual pathology, transcranial approach was achieved to prevent permanent visual loss. The final pathological diagnosis was pituicytoma with epithelioid features. Pituicytoma is a rare low-grade tumor (WHO Grade I) of pituicytes involving the sellar and suprasellar region, and originating from special glial cells of the neurohypophysis. Because of the high vascularity, the firm consistency, and invasion to surrounding neurovascular structures, a pituicytoma should be included in the differential diagnosis of a mass in the sellar and suprasellar area if the tumor shows high enhancement with vascular components. We report a case of rare pituicytoma mimicking a pituitary macroadenoma with massive hemorrhage to disturb surgery.

Keywords: Enhancement; Hemorrhage; Pituicytoma; Pituitary macroadenoma.

Fig. 1. Preoperative magnetic resonance imaging. T1-weighted axial image (A) showing slightly hyperintense sellar mass, T2-weighted axial image (B) showing isointense sellar mass, and T1-weighted gadolinium enhanced coronal (C) and sagittal (D) images demonstrating marked enhancement of sellar-suprasellar mass with involvement of the optic nerves and chiasm.

Fig. 2. Angiograms of right (A) and left (B) internal carotid arteries showing significant tumor blush in the arterial phases by multiple small feeders from both internal carotid arteries.

Fig. 3. Histopathological findings of the pituicytoma. A: The tumor cells have moderate to abundant amount of pale eosinophilic cytoplasm and ovoid nuclei with small nucleoli. Necrosis is not identified (hematoxylin and eosin staining, ×400). B: Immunohistochemistry for glial fibrillary acidic protein shows focal positivity (×400). C: The tumor cells are positive for S100 protein (×400). D: The tumor cells show positive staining for thyroid transcription factor 1 (×400).

Fig. 4. Postoperative magnetic resonance imaging after transcranial approach. T1-weighted gadolinium enhanced coronal (A) and sagittal (B) images show total removal of the suprasellar tumor that compressed the optic chiasm and remnants attached to both cavernous sinuses.