Variability in Clinical Presentation and Pathologic Implications of Ectopic Pituitary Tumors: Critical Review of Literature

OBJECTIVE: Pituitary tumors are common, well-described skull base tumors of sellar origin. However, there are reports of rare ectopic pituitary tumors that are found exclusively outside of the sella turcica. Ectopic pituitary tumors have not been holistically analyzed. This study describes presentation and clinical patterns found among patients with ectopic pituitary tumors. METHODS: A comprehensive review of the literature was performed for clinical descriptions of ectopic pituitary tumors. Reports of 85 applicable cases were evaluated. RESULTS: The most common locations of ectopic pituitary tumors were the sphenoid sinus, clivus, suprasellar space, nasopharynx, and cavernous sinus. The majority of ectopic pituitary tumors were reported as being functional secretory tumors; they were statistically significantly more likely to be functional tumors than sellar pituitary tumors. Adrenocorticotrophic hormone, prolactin, growth hormone, and thyroid-stimulating hormoneLsecreting tumors were most commonly found. Bone invasion was reported in more than one third of the cases, and malignant transformations were reported in 6 cases. A large majority of patients presented with hormonal, neurologic, or physiologic symptoms. CONCLUSIONS: Ectopic pituitary tumors are a rare entity of pituitary tumors with a presentation that can mimic those of other skull base tumors. Clinical presentation often correlates to location of the tumor. Ectopic pituitary tumors were significantly more likely to be functional secretory tumors. They may also exhibit more aggressive behavior than sellar-located tumors. Ectopic pituitary tumors may be part of a spectrum of presenting pathologies. Further genetic or genomic analysis is necessary to better understand their pathogenesis and clinical presentations.