Pituitary macroadenoma: less common neuroimaging features in a common lesion

Pituitary neuroendocrine tumors, previously known as pituitary adenomas, are the most common pituitary gland tumors; when larger than 10 mm in diameter, they are called pituitary macroadenomas. Although most pituitary macroadenomas exhibit characteristic imaging features, some present with uncommon neuroimaging manifestations. Less common imaging manifestations include hemorrhage, areas of necrosis, cystic components, calcifications, bone invasion, and extrasellar location. Knowing how to recognize the atypical neuroimaging patterns of pituitary macroadenomas is also crucial for identifying the potential aggressive behavior of the lesion. In addition to predicting aggressive behavior, recognition of atypical neuroimaging characteristics can help the neurosurgeon determine the most effective surgical approach. The aim of this review was to highlight the less common imaging patterns of pituitary macroadenomas.