The impact of pituicytoma on hormone secretary function

Background: Pituicytes are glial cells supporting hypothalamic axons in the posterior pituitary gland. Pituicytoma arises from pituicytes, and is currently classified as a World Health Organization grade I central nervous system tumor. Clinically, some patients with pituicytoma are misdiagnosed with functioning pituitary adenoma before surgical interventions and pathological examinations. This study was designed to investigate the correlation between pituicytoma and abnormal hormone function. Methods: The records of patients who underwent pituitary surgery at Linkou Chang Gung Memorial Hospital between 2000 and 2016 were reviewed. Patients with a pathological diagnosis of pituicytoma were included. Among these patients, those with inadequate data and/or specimens were excluded. Clinical information including presenting symptoms, serum hormone level, neuroimages, and results of pathological examinations including hematoxylin and eosin stains and immunohistochemical stains were collected for analysis. Results: Between 2000 and 2016, eight patients were pathologically diagnosed with pituicytoma. Two patients were excluded due to missing data and/or specimens. Among the six remaining patients, five presented with hormone changes. The immunohistochemical stains of pituicytoma confirmed no secretory function; however, the surrounding pituitary glandular tissue showed positive results responsible for clinical hormone changes. Conclusions: Pituicytoma had a negative endocrine secretory function in this study. However, pituicytoma was associated with hyperactivity of the surrounding pituitary glandular tissue, which resulted in clinically abnormal hormone secretion. The diagnosis of pituicytoma before a thorough pathological examination is difficult when the patients present with hormone dysfunction. Therefore, maximum resection of the pituitary tumor is necessary to make the diagnosis of pituicytoma and to exclude pituitary adenoma. Keywords: Pituicytoma, Pituitary gland, Abnormal hormone secretion, Pituitary adenoma, Immunohistochemical stain