Endoscopic Endonasal Resection of a Hypothalamic Pilomyxoid Astrocytoma: Case Report

Background: Pilomyxoid astrocytoma (PMA) is a rare, relatively aggressive, variant of pilocytic astrocytoma (PA) typically occurring in the hypothalamic and suprasellar region. This report represents, to our knowledge, the first case of PMA of the suprasellar region presenting with apoplexy and resected by an endoscopic endonasal approach (EEA).

Case Presentation: A 27-year-old female presented after awakening with an excruciating headache, self-described as the “worst headache of her life,” originating in her occiput and radiating toward her right eye. She also complained of blurry vision, lightheadedness, nausea, and vomiting. Her history was significant for amenorrhea and hypothalamic hypogonadism managed by oral contraception. A CT scan demonstrated perimesencephalic subarachnoid hemorrhage ([Fig. 1A]). Detailed vascular imaging did not reveal a specific cause ([Fig. 1B]). An MRI showed a heterogeneous, multilobulated sellar, and suprasellar hemorrhagic mass extending into the third ventricle and posterior fossa ([Fig. 2A–C]). She was also found to have low am cortisol. Pursuant to these findings, the differential diagnosis was expanded to include papillary craniopharyngioma, pituitary adenoma with apoplexy, and intrinsic hypothalamic tumors.

The patient was taken to the operating room for an endoscopic endonasal resection of the mass. After raising a nasoseptal flap, we began with a suprasellar approach, but after the diagnosis confirmed a low-grade glial tumor, we proceeded to perform posterior clinoidectomies, and a transcavernous pituitary transposition, for extension of the dural opening across the dorsum and into the posterior fossa. A gross total resection of the lesion was achieved, which had evident hemorrhagic components within it. The pituitary gland was displaced inferiorly, while the stalk was displaced to the left. At the end of the resection, a panoramic view of the posterior fossa vasculature, as well as the third ventricle was seen ([Fig. 3]). The defect was reconstructed with a fascia lata graft, and a nasoseptal flap.

The patient recovered rapidly and was discharged home. The final integrated morphologic and molecular diagnosis was pilomyxoid astrocytoma ([Fig. 4]). K_i-67 proliferation was detected in <1% of cells and a PTPN11 mutation was identified. Postoperative imaging confirmed a gross total resection ([Fig. 2D–E]). She is currently treated for hypothyroidism with levothyroxine and for persistent adrenal insufficiency with hydrocortisone. No adjuvant therapy was administered, and she is being followed-up with serial imaging.

Conclusion: Hypothalamic pilomyxoid astrocytomas should be included in the differential diagnosis of apoplexy, particularly in younger patients with extensive sellar/suprasellar lesions. These tumors can often be completely addressed through an endonasal surgical corridor.

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Publication History

Article published online:
12 February 2021