Pituitary Anomalies


KEY FACTS

Terminology

  • Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction

Imaging

  • Posterior pituitary ectopia (PPE)

  • Duplicated pituitary gland/stalk (DP)

  • PPE: No (or tiny) pituitary stalk, ectopic posterior pituitary on midline sagittal T1WI MR

    • Look for associated anomalies: Heterotopia, optic nerve hypoplasia, corpus callosum anomalies

  • DP: 2 pituitary stalks on coronal view, thick tuber cinereum on midline sagittal view

Top Differential Diagnoses

  • PPE

    • Surgical or traumatic stalk transection

    • Central diabetes insipidus

    • Hypothalamic lipoma (in tuber cinereum)

  • DP

    • Dilated infundibular recess of 3rd ventricle (“pseudoduplication”)

    • Tuber cinereum hamartoma

Pathology

  • PPE: Genetic mutation → defective neuronal migration during embryogenesis

  • DP: Genetic mutation unknown; may constitute polytopic field defect due to splitting of notochord

Clinical Issues

  • PPE: Short stature

  • DP: Unsuspected finding on craniofacial imaging for other indications

Diagnostic Checklist

  • PPE: Assess optic and olfactory nerves, frontal cortex

  • DP: Oral tumors compromise airway patency

Sagittal graphic demonstrates ectopia of the posterior pituitary gland
located at the distal end of a truncated pituitary stalk along the median eminence of the hypothalamus. The sella turcica and adenohypophysis
are both small.

Sagittal T1WI MR shows an ectopic posterior pituitary gland located at the median eminence
. The pituitary infundibulum is absent, the anterior pituitary gland
is small, and the normal bright posterior pituitary gland is not identified in its typical location.

Coronal T1WI MR depicts the ectopic posterior pituitary gland location at the median eminence
. A pituitary stalk is not visualized below the ectopic posterior pituitary. The septum pellucidum is present, and the optic tracts
are of normal size.

Sagittal T2 MR in a patient with complete absence of the posterior pituitary bright spot shows a small sella turcica and pituitary gland
. The optic apparatus
is also hypoplastic. A clearly defined pituitary stalk
is present.

TERMINOLOGY

Synonyms

  • Ectopic pituitary bright spot

Definitions

  • Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction

IMAGING

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