The evolution in pituitary tumour classification: a clinical perspective.

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Pituitary tumours are a diverse group of neoplasms with evolving classification systems.
• Understanding tumour biology has driven dramatic changes in classification over the past two decades.

Purpose of the Study:

• To review the evolution of pituitary tumour classification from a clinical perspective.
• To examine the impact of changing classification frameworks on diagnosis and management.

Main Methods:

• Narrative review of pituitary tumour classification systems.
• Analysis of historical and current World Health Organization (WHO) guidelines.
• Examination of diagnostic markers including Ki67, mitotic count, p53, transcription factors, and hormonal immunohistochemistry.

Main Results:

• The 2004 classification used 'typical' or 'atypical' based on proliferation markers (Ki67, mitotic count, p53).
• The 2017 WHO classification shifted to a lineage-based system using transcription factors and hormonal immunohistochemistry, omitting 'typical'/'atypical' terms.
• The 2022 WHO classification introduced further refinements, recognizing less common types and identifying 'high risk' tumours, though prognostication needs improvement.

Conclusions:

• Recent WHO classifications represent substantial progress in the diagnostic evaluation of pituitary tumours.
• Challenges persist for clinicians and pathologists in managing these neoplasms.
• Further research is needed to enhance the prognostication of pituitary tumours.