Histopathological classification of non-functioning pituitary neuroendocrine tumors

Aggressive and malignant pituitary tumours: state-of-the-art

Pituitary adenomas are unique in multiple ways. They are rarely malignant in terms of metastases; yet, they may be aggressive. Their cancerous potential is defined in a classic oncological way by the ability to metastasise, and therefore, it has been crucial to differentiate this process from aggressive behaviour, characterised as a particularly invasive and/or recurrent behaviour and resistance to common modalities of therapy. Recently, however, important changes have been introduced to the diagnosis and management of aggressive and malignant pituitary tumours including the 4th edition of the World Health Organization (WHO) classification for endocrine tumours (2017) as well as ESE Clinical Guidelines (2018), although an attempt to establish predictive and/or prognostic markers of clinical aggressiveness remains difficult. In this review, we focus on a group of pituitary tumours causing significant problems in clinical practice and requiring multidisciplinary input. We summarise updates in definitions of tumour invasiveness, aggressiveness and malignant transformation, as well as histological classification, and emphasise the new considerations regarding aggressive and malignant potential and its relationship to therapeutic strategies.

Giant pituitary adenoma: histological types, clinical features and therapeutic approaches

Giant pituitary adenomas comprise about 6-10% of all pituitary tumors. They are mostly clinically non-functioning adenomas and occur predominantly in males. The presenting symptoms are usually secondary to compression of neighboring structures, but also due to partial or total hypopituitarism. Functioning adenomas give rise to specific symptoms of hormonal hypersecretion. The use of dopamine agonists is considered a first-line treatment in patients with giant macroprolactinomas. Somatostatin analogs can also be used as primary treatment in cases of growth hormone and thyrotropin producing giant adenomas, although remission of the disease is not achieved in the vast majority of these patients. Neurosurgical treatment, either through transsphenoidal or transcranial surgery, continues to be the treatment of choice in the majority of patients with giant pituitary adenomas. The intrinsic complexity of these tumors requires the use of different therapies in a combined or sequential way. A multimodal approach and a therapeutic strategy involving a multidisciplinary team of expert professionals form the basis of the therapeutic success in these patients.

Nonfunctioning Pituitary Adenoma Recurrence and Its Relationship with Sex, Size, and Hormonal Immunohistochemical Profile

BACKGROUND

Tumor recurrence or incomplete resection in nonfunctioning pituitary adenomas (NFPAs) is relatively common. However, predictive factors of tumor recurrence in NFPAs are not well established. We evaluated possible factors related to tumor recurrence in a large cohort of NFPAs at a single pituitary neurosurgery center.

METHODS

A retrospective analysis was conducted of 410 medical records of patients with NFPAs treated by transsphenoidal surgery between 2000 and 2014.

RESULTS

Among the participants, 210 were female (51.0%). A total of 14.1% had giant adenomas. Null-cell pituitary adenomas (n = 239; 58.9%) were the most frequent, followed by silent gonadotroph adenomas (n = 112; 27.3%). Null-cell adenomas were more frequent in women (P = 0.008) and silent gonadotroph adenomas were more frequent in men (P = 0.004). Recurrence was not related to sex or age. Tumor recurrence occurred more often among silent corticotropic adenomas and giant adenomas (hazard ratio 2.45; P < 0.0001 and hazard ratio 2.35; P = 0.001, respectively). Silent thyrotrophic adenoma presented a comparable frequency of recurrence of silent corticotropic adenomas, despite having borderline significance (P = 0.07).

CONCLUSIONS

NFPA tumors have a high heterogeneous hormonal profile and may have prognostic importance. Silent corticotropic adenomas and giant adenomas present a high rate of recurrence.

Recurrent non-functioning pituitary adenomas: a review on the new pathological classification, management guidelines and treatment options

At least 50% of surgically resected non-functioning pituitary adenomas (NFPA) recur. Either early or late adjuvant radiotherapy is highly efficacious in controlling recurrent NFPA but associates potentially burdensome complications like hypopituitarism, vascular complications or secondary neoplasm. Reoperation is indicated in bulky tumor rests compressing the optic pathway. To date, no standardized medical therapy is available for recurrent NFPA although cabergoline and temozolomide show promising results. Guidelines on the management of recurrent NFPAs are now available. The new 2017 WHO pituitary tumor classification, based on immunohistochemistry and transcription factor assessment, identifies a group of aggressive NFPA variants that may benefit from earlier adjuvant therapy. Nevertheless, NFPA patients exhibit a reduced overall life expectancy largely due to hypopituitarism and treatment-related morbidity. The management of recurrent NFPA benefits from a multidisciplinary teamwork of surgeons, endocrinologists, radiation oncologists, ophthalmologists, pathologists and neuro-radiologists in order to provide individualized therapy and anticipate deterioration.