Endocrine Abstracts

Background: Posterior pituitary tumors (PPTs) present as clinically nonfunctioning space-occupying lesions of the sellar region. The diagnosis of PPTs is not possible on the basis of their clinical, radiological and biochemical features. Immunohistochemistry identifies them for their expression of TTF. They are virtually always mistakenly defined as one of the more common pituitary tumours. Due to their rarity, the long-term endocrine aspects and outcomes of PPTs are not well known.

Objective: The objective was to evaluate the clinical characteristics, surgical approaches, and survival of a single-center cohort of patients with PPTs who underwent surgical treatment at our institution.

Methods: 19 patients (11 females and 8 males) with histologically confirmed PPTs were identified between the years 1982 and 2022 out of 8761 operated sellar lesions. Their data were retrospectively collected and analyzed.

Results: There were 3 pituicytoma (PC), 8 granular cell tumor (GCT), and 8 spindle cell oncocytoma (SCO) subtypes of what today all is called pituicytoma. The mean age at diagnosis was 58.65±13.6 years (range 27-75). The most common presenting symptoms were visual disturbance and headache (47% each), followed by dizziness (26%) and decreased libido/erectile dysfunction (16%). Preoperative MRI scans were not predictive of PPTs. Preoperative endocrine dysfunction consisted of hypocortisolemia and hypogonadism (42% each), hyperprolactinemia and hypothyroidism (37% each). After surgery, corticotropic and gonadotropic dysfunction remained unchanged. A statistically significant reduction/normalization of prolactin levels was detected (P<0.05). Diabetes insipidus was observed in one patient preoperatively and in two patients postoperatively. The mean tumor volume was 2.14 ± 2.01 cm³ (range 0.12-7.37). In most patients the surgery was performed through a transcranial approach (58%) and in 8 cases the transsphenoidal approach was used (42%). Gross total resection was achieved in 11 patients (58%). The mean follow-up in months was 58.89 ± 43.13.5 (median 63 [range 3-150]). Recurrence was observed in 3/19 (16%) patients.

Conclusion: PPTs are benign neoplasms and do not have specific presenting clinical, endocrinological and imaging findings. Histopathological examination with confirmation of TTF expression remains crucial in the diagnosis. The location and invasive growth with suprasellar tumour extension in this patient cohort makes them not amenable to total resection and more often dictates a transcranial approach as opposed to transsphenoidal surgery.