Pituitary Hyperplasia

KEY FACTS

Terminology

• Upper limit of normal pituitary height varies with age, sex

  • Pregnant/lactating female patients: 12 mm

  • Young menstruating female patients: 10 mm

  • Male patients, postmenopausal women: 8 mm

  • Infants, children: 6 mm

• Nonphysiologic hyperplasia seen with

  • Hypothyroidism, Addison disease, or other end-organ failure

  • Some neuroendocrine neoplasms

Imaging

• Enlarged homogeneously enhancing pituitary gland with convex superior margin

• Best technique: High-resolution MR

  • Sagittal/coronal T1; coronal T2

  • Dynamic coronal T1WI

  • Postcontrast T1 FS sagittal/coronal T1

  • 3-4-mm slice thickness

Top Differential Diagnoses

• Pituitary macroadenoma

• Pituitary microadenoma

• Lymphocytic hypophysitis

• Venous congestion (intracranial hypotension, dural arteriovenous fistula)

Pathology

• Growth hormone cell hyperplasia usually diffuse, occurs with neuroendocrine tumors

• Prolactin cell hyperplasia: Diffuse > nodular

• Corticotroph hyperplasia: Nodular or diffuse

• Thyrotroph hyperplasia

  • Longstanding primary hypothyroidism, may have associated prolactin hyperplasia

• Gonadotroph hyperplasia (e.g., Turner, Klinefelter syndrome)

TERMINOLOGY

IMAGING