Vestibular schwannoma and pituitary adenoma in the same patient: coincidence or novel clinical association?

Over the years the authors have evaluated a number of patients with vestibular schwannomas (VS) who have also been diagnosed with a pituitary adenoma (PA). No associations between these tumors have been established to date. The objective of the current study is to investigate the epidemiological association between VS and PA via a population-based study and to supplement these data with a retrospective case series of 12 patients who were evaluated at the authors' center over the past 15 years. An analysis of the Surveillance, Epidemiology, and End Results database including all patients identified with a diagnosis of VS and/or PA was performed. A comparison between the observed and expected annual incidence was calculated and population differences between those with VS + PA were compared with single tumor populations. 9888 patients with VS and 26,577 patients with PA were identified among 822.9 million person-years. Within these populations, 31 patients were diagnosed with both tumor types. Overall, 1 in every 319 patients with VS was also diagnosed with a PA. The average annual incidence for VS was 1.2 per 100,000 persons per year while the average PA rate was 3.2 per 100,000 persons per year. The observed rate of co-incident VS and PA was greater than what is expected by chance alone assuming independence. The cohort of patients with coexisting VS and PA were older and more commonly male compared to VS-only or PA-only groups. These data strongly suggest that a common environmental or genetic predisposition exists for VS and PA development. Further study of this population may help elucidate the cause of tumorigenesis in a subset of patients with seemingly sporadic tumors.