A 30-year-old woman has hyperprolactinemia, secondary amenorrhea, and MRI shows a 1.5 cm pituitary mass (macroadenoma). Surgical pathology: immunostaining for prolactin is positive but the Ki-67 labeling index is 12% and p53 is strongly positive. The 2022 WHO classification of pituitary tumors introduced a new term for pituitary adenomas to replace the traditional term. These tumors are now called:

• A Pituitary carcinoma — reserved for tumors with distant metastases
• B Pituitary neuroendocrine tumors (PitNETs), with 'aggressive' pituitary neuroendocrine tumor for high Ki-67/p53-positive tumors ✓
• C Prolactinoma — no terminology change in WHO 2022
• D Pituitary blastoma — WHO 2022 new entity for all functioning adenomas

Explanation

The 2022 WHO Classification of Endocrine and Neuroendocrine Tumors renames pituitary adenomas as pituitary neuroendocrine tumors (PitNETs) to align with the broader neuroendocrine tumor classification framework and to acknowledge their neoplastic nature more accurately. High-risk PitNETs with Ki-67 ≥3%, high mitotic count, and p53 positivity are classified as 'aggressive PitNETs' (formerly 'atypical adenomas'), which have a higher recurrence rate and may require adjuvant therapy. True pituitary carcinoma requires demonstrated cerebrospinal or systemic metastasis and is very rare.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

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Written and medically reviewed by the StethoPrep medical team.