EPID-35. COLLISION TUMORS AT THE SKULL BASE: UNVEILING A PETROCLIVAL MENINGIOMA COEXISTING WITH A GROWTH HORMONE-PRODUCING PITUITARY ADENOMA

Abstract

Abstract Collision tumors are rare occurrences characterized by coexistence of two histologically different tumor types within the same anatomical location. While collision tumors involving skull base meningiomas and pituitary adenomas are uncommon, they pose distinct diagnostic challenges. We report the case of a 57-year-old female initially diagnosed with petroclival meningioma WHO 1, subsequently found to harbor a collision tumor with a growth hormone-producing pituitary adenoma. The patient initially presented with aphasia, right-sided weakness, and gait instability, prompting a diagnosed of left petroclival mass with left temporal horn entrapment. Patient underwent craniotomy and partial resection of the tumor in 2022 and was diagnosed with meningothelial meningioma, WHO1. The patient had history of uncontrolled diabetes and physical features of large hands with hypertrophied terminal phalangeal tufts but patient reported that she has had similar hands since childbirths for decades. Screening pituitary function tests were ordered due to the petroclival meningioma involving suprasellar region, revealing significantly elevated growth hormone, and insulin-like growth factor-1(IGF-1) levels, raising suspicion for pituitary adenoma. Subsequent endoscopic resection of the sellar mass via a transsphenoidal approach in 2024 confirmed the presence of somatotroph pituitary neuroendocrine tumor. Retrospectively growth hormone producing pituitary adenoma likely contributed to patient’s uncontrolled diabetes and coarse, large hands. This case highlights the importance of a high index of suspicion for collision tumors, particularly in patients with skull base tumors involving supra sellar region, especially when presenting with atypical clinical features.