Pituicytoma Associated with Serum Adrenocorticotropic Hormone Elevation

Background: Pituicytoma is a rare benign tumor of the neurohypophysis or hypophyseal stalk. Endocrinological abnormalities derived from this tumor are even rarer. Although three cases of pituicytoma with elevated plasma adrenocorticotropic hormone (ACTH) have been reported previously, the etiological mechanisms remain unknown. Case Description: We present a 47-year-old woman who was referred to a hospital complaining of headache. On investigation using magnetic resonance imaging (MRI), a tumor was detected in the sellar region. Elevation of basal ACTH and serum cortisol was identified, suggesting an ACTH-producing pituitary adenoma. However, physical findings and results of other hormonal examination showed no evidence of Cushing disease. The tumor had been detected incidentally eight years earlier when MRI was performed, and showed considerable enlargement on this consultation. Endoscopic endonasal transsphenoidal surgery was performed in order to remove the tumor completely. The histopathological diagnosis was pituicytoma. The patient’s postoperative clinical course was excellent, and both ACTH and cortisol levels returned to normal following surgery. Conclusions: It appears that ACTH was being secreted from the tumor cells. We discuss the possible mechanism of ACTH elevation in cases of pituicytoma.