Endocrine Abstracts

Introduction

Prolactinomas are the most frequent pituitary tumors. They are usually benign with a good response to conventional medical treatment by dopaminergic agonists (DA). However in some cases, prolactinomas are defined as invasive or aggressive according to clinical, radiological, biological and histopatholgical arguments. The aim of our case report is to discuss potential predictors of aggressiveness in prolactine secreting pituitary tumors.

Case report

A 56 year-old female patient, was admitted in hospital for a giant pituitary adenoma revealed by opto-chiasmatic syndrome. MRI showed a giant macroadenoma measuring 54 × 50 × 54 mm with latero supra and infrasellaire extension and lytic lesions of sphenoid bone and clivus. Hormonal explorations showed a hyperprolactinemia of 48 658 ng/ml (monomeric prolactin represented 95% of total prolactin ruling out a macroprolactinemia) with a secondary gonadal and corticotropic defiencency. Partial transcranial adenomectomy was performed then cabergoline was started at 1 mg/week. Histological assessment confirmed a macroadenoma with a Ki67 of 5%. Follow up imaging and biological assessement are in progress.

Discussion

Aggressive pituitary tumors (APTs) are defined as radiologically invasive tumors with an unusually rapid tumor growth rate, or relevant tumor growth despite optimal standard therapies. The World Health Organization 2017 classification of pituitary tumors abandoned the previous term ’atypical pituitary adenoma’ and categorizes prolactinomas into PRL-producing adenomas and APTs or carcinomas in case of metastases. Invasiveness alone is insufficient to define APTs, but is still considered as a key component of aggressiveness. APTs typically evolve from macroadenomas with lactotroph and corticotroph tumors predominating. In our case, the giant prolactinoma with invasive radiological signs and lytic bone lesions were suggestive of aggressiveness. However, radiological and biological evolution after surgical and correctly conducted medical treatment will settle the diagnosis.

Conclusion

Prolactinomas are the most frequent secreting pituitary tumors. Their treatment is well established due to their good response to DA. However, some cases can be invasive with a rapid growth pattern. Predictive factors of aggressiveness are not well defined but tumor size, early radiological signs of invasiveness as well as histological assessement may be suggestive of such entity.