Enlarged Pituitary Gland

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Not all “enlarged pituitary glands” are abnormal!
- Size/height varies with gender, age
  - Children = 6 mm
  - Males, postmenopausal females = 8 mm
  - Young menstruating females = 10 mm (can bulge upwards)
  - Pregnant, postpartum lactating females = 12 mm
- Enhances strongly, uniformly
  - 15-20% have incidental cyst or nonfunctioning microadenoma (pituitary “incidentaloma”)
Variants/mimics of “enlarged pituitary”
- “Pseudoenlargement” secondary to unusually shallow bony sella
- Medially positioned cavernous internal carotid arteries (“kissing carotids”) may make gland appear enlarged

Helpful Clues for Common Diagnoses

Pituitary Hyperplasia
- Can be normal (young menstruating females)
- Enlarged gland ± upward bulging
- May be related to end-organ failure or neuroendocrine tumors
Pituitary Microadenoma
- May enlarge gland
- Best identified with dynamic, contrast-enhanced MR
Pituitary Macroadenoma
- Pituitary gland can’t be distinguished from mass
- Enhances strongly, often heterogeneously

Other Essential Information

Venous congestion (intracranial hypotension, dAVF) can enlarge gland
Beware: Child or young adolescent male with “pituitary adenoma” most likely has pituitary hyperplasia, not neoplasm!
- Evaluate for end-organ failure (e.g., hypothyroidism)