Transsphenoidal Posterior Pituitary Lobe Biopsy in Patients with Neurohypophysial Lesions

Objective The differential diagnosis of neurohypophysial lesions is difficult, and surgical biopsies are indispensable in the histologic diagnosis of some patients. Although pituitary stalk biopsies are uniformly performed, there is a considerable risk that they will result in impaired hormonal secretion. We attempt to clarify the usefulness and safety of posterior pituitary lobe biopsy by transsphenoidal surgery (TSS). Methods The cases of 11 consecutive patients who underwent posterior pituitary lobe biopsies by TSS were retrospectively studied. Patients with cystic sellar lesions were excluded. We examined the clinical findings, endocrinologic data, magnetic resonance imaging findings, and histologic diagnoses of the patients. The locations of neurohypophysial lesions and the histologic diagnoses by posterior pituitary lobe biopsies were examined. Results The major preoperative clinical symptoms were diabetes insipidus (DI) (90.9%), followed by anterior pituitary lobe dysfunction (hypopituitarism) (54.5%). In all the patients, the lesions occupied the pituitary stalk and the posterior pituitary lobe, and the bright spot, which would indicate a normal posterior pituitary gland, disappeared on T1-weighted imaging. The posterior pituitary lobe specimens could be histologically diagnosed in all these cases. DI persisted in 10 patients with preoperative DI after the biopsy, whereas the 1 patient without preoperative DI did not suffer from DI after the biopsy. Conclusions A posterior pituitary lobe biopsy by TSS may be an alternative to pituitary stalk biopsy in patients with neurohypophysial lesions.