Incidence of Primary Pituitary Neuroendocrine Tumors (PitNETs)
The incidence of primary pituitary neuroendocrine tumors (excluding metastatic PitNET and pituitary carcinoma) ranges from approximately 1-4 cases per 100,000 population per year, with significant variation by age group and detection methods. 1
Age-Specific Incidence Patterns
The incidence of pituitary adenomas increases dramatically with age, showing distinct patterns across the lifespan:
Pediatric and adolescent populations (0-19 years): Between 1997-2016 in the UK, only 5 children aged 0-4 years were diagnosed, 14 children aged 5-9 years, 78 young people aged 10-14 years, and 282 young people aged 15-19 years, demonstrating that these tumors represent only 1% of all intracranial neoplasms before age 15 but increase to 18% in patients aged 15-24 years 1
Adult populations: The highest incidence occurs from the fifth decade onwards, with pituitary adenomas representing 78% of pituitary fossa lesions in children and young people overall 1
Detection vs. True Incidence
There is a substantial discrepancy between clinical and autopsy findings that reveals the true burden of disease:
Clinical incidence: Approximately 3.0-5.25 cases per 100,000 population per year based on diagnosed cases 1
Autopsy incidence: Significantly higher at 8.4 per 100,000 per year, indicating that many pituitary tumors remain undiagnosed during life 1
This gap suggests that improved imaging techniques and diagnostic protocols are detecting previously occult tumors rather than representing a true increase in disease occurrence 1, 2
Important Clinical Context
Genetic Syndromes Present Earlier
Patients with inherited syndromes such as MEN1 (associated with menin gene mutations) may develop pituitary tumors 15 years earlier than those with sporadic tumors, typically presenting with multiple tumors of the parathyroid, pituitary, and pancreatic glands 1
Tumor Characteristics in Younger Patients
Large pituitary adenomas (macroadenomas ≥1 cm and giant adenomas >4 cm) are more prevalent in children and young people than in adults, and these patients more commonly present with mass effects including visual field defects, hypothalamic dysfunction, and raised intracranial pressure 1
Critical Diagnostic Pitfalls
Many pituitary tumors present late in children and adolescents because characteristic signs such as pubertal delay, amenorrhea, or rapid growth velocity may be occult or missed during development. 1 This delayed recognition contributes to the higher proportion of macroadenomas at diagnosis in younger populations compared to adults.
The increasing reported incidence over recent decades is primarily attributable to improved detection through advanced imaging modalities, particularly somatostatin receptor imaging, which identifies smaller, earlier-stage tumors that would have been missed previously 2