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---
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title: "Pituitary Anomalies"
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docid: "09ca9b54-a3d9-43fd-a9cc-4c0212b578a1"
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breadcrumbs:
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- "Brain"
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- "Diagnosis"
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- "Anatomy-Based Diagnoses"
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- "Sella and Pituitary"
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- "Congenital"
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- "Pituitary Anomalies"
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---
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# KEY FACTS
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- ## Terminology
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- Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction
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- ## Imaging
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- Posterior pituitary ectopia (PPE)
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- No (or tiny) pituitary stalk, ectopic posterior pituitary (EPP) on midline sagittal T1WI MR
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- Look for associated anomalies: Heterotopia, optic nerve hypoplasia, corpus callosum anomalies
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- Duplicated pituitary gland/stalk (DP)
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- 2 pituitary stalks on coronal view, thick tuber cinereum on midline sagittal view
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- ## Top Differential Diagnoses
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- PPE
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- Surgical or traumatic stalk transection
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- Central diabetes insipidus
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- Hypothalamic lipoma (in tuber cinereum)
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- DP
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- Dilated infundibular recess of 3rd ventricle ("pseudoduplication")
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- Tuber cinereum hamartoma
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- ## Pathology
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- PPE: Genetic mutation → defective neuronal migration during embryogenesis
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- DP: Genetic mutation unknown; may constitute polytopic field defect due to splitting of notochord
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- ## Clinical Issues
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- PPE: Short stature
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- DP: Unsuspected finding on craniofacial imaging for other indications
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- ## Diagnostic Checklist
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- PPE: Assess optic and olfactory nerves, frontal cortex
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- DP: Oral tumors compromise airway patency
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# TERMINOLOGY
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- ## Synonyms
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- Ectopic pituitary bright spot
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- ## Definitions
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- Congenital anomalies of pituitary stalk → potential hypothalamic/pituitary axis malfunction
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# IMAGING
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- ## General Features
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- ### Best diagnostic clue
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- Posterior pituitary ectopia (PPE): No (or tiny) pituitary stalk, ectopic posterior pituitary (EPP) on midline sagittal T1WI MR
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- Partial pituitary ectopia also reported
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- Duplicated pituitary gland/stalk (DP): 2 pituitary stalks on coronal view, thick tuber cinereum on midline sagittal view
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- Tuberomammillary fusion: Tuber cinereum/mammillary bodies fused into single mass
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- Pituitary hypoplasia: Small sella turcica and adenohypophysis
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- ### Location
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- PPE: EPP located along median eminence of tuber cinereum or truncated pituitary stalk
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- DP: Paired lateral stalks, pituitary glands, bony fossae
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- ### Size
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- PPE: Anterior pituitary (adenohypophysis) is small
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- DP: Each pituitary gland is normal in size
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- ### Morphology
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- PPE: Small adenohypophysis and osseous sella
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- DP: Each pituitary gland and osseous sella is normal in morphology but laterally located
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- ## Radiographic Findings
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- ### Radiography
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- PPE: Small sella turcica on lateral view
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- DP: Craniofacial/craniocervical anomalies common; may observe 2 fossae on AP view
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- ## CT Findings
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- ### NECT
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- PPE: Narrow pituitary fossa and skull base structures and clivus, ± persistent sphenopharyngeal foramen
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- DP: 2 widely separated pituitary fossae, ± midline basisphenoid cleft or frontonasal dysplasia
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- ### CTA
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- PPE: Medial deviation of juxtasellar/supraclinoid carotid arteries ("kissing" carotids)
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- DP: Duplicated basilar artery (BA), ± widely separated juxtasellar/supraclinoid carotid arteries
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- ## MR Findings
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- ### T1WI
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- PPE: Absent, truncated, or thread-like pituitary stalk; small adenohypophysis
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- EPP located along truncated stalk or median eminence of tuber cinereum
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- Usually ↑ signal on T1WI (phospholipids/secretory granules)
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- Posterior pituitary may "dim" as patient outgrows available hormone levels
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- Chiari 1 (20%), ± olfactory hypoplasia, frontal lobe dysgenesis/migration anomalies
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- ± absent septum pellucidum, ocular dysgenesis, hypoplastic optic nerves/chiasm
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- DP: Mass-like thickening of tuber cinereum on sagittal view portends duplicated pituitary axis
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- Mammillary bodies fused with tuber cinereum into thickened 3rd ventricle floor
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- 2 lateralized but otherwise normal pituitary glands/stalks
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- Brain anomalies: Callosal dysgenesis, duplicated anterior 3rd ventricle, cleft brainstem, Dandy-Walker malformation
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- Cranial nerve anomalies: Olfactory nerve and optic nerve hypoplasia
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- Oral tumors: Epignathus (giant teratoma) or dermoid (mixed signal), lipoma (↑ T1WI)
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- ### T2WI
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- PPE: Variable signal of posterior pituitary
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- DP: Normal signal of glands, stalk, tuberomammillary fusion mass
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- ### T1WI C+
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- Both: Stalks and remnants enhance (absent blood-brain barrier)
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- PPE: Hyperintensity absent if multiple endocrine anomalies/diabetes insipidus; contrast enhancement helps find neurohypophysis
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- ### MRA
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- PPE: Supraclinoid carotid arteries medially deviated, "kiss" in midline; rare absent carotid artery/canal
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- DP: Fenestration (common) or total duplication (rare) of BA; widely separated juxtasellar carotid arteries
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- ### MRV
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- Used to characterize torcular and straight sinus anomalies if midline posterior fossa anomaly identified
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- ## Angiographic Findings
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- Conventional
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- PPE: Variable deviation "kissing" carotids (37%)
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- DP: Split/duplicated BA, ± lateral deviation carotids
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- ## Imaging Recommendations
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- ### Best imaging tool
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- Multiplanar T1WI MR
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- ### Protocol advice
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- Both: Sagittal and coronal T1WI ± T2WI of hypothalamic/pituitary axis
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- PPE: Assess olfactory nerves, anterior frontal lobes with coronal T2WI
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- 3D T1WI SPGR can identify small posterior pituitaries, occult on conventional 2D sagittal T1WI
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- DP: 3D CT of skull base and face in selected patients
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# DIFFERENTIAL DIAGNOSIS
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- [Posterior Pituitary Ectopia](/document/pituitary-anomalies/556da02b-74c3-489a-8aed-ebbc97b620fa)
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- **Central diabetes insipidus**
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- Hyperintensity of posterior pituitary lobe is absent but normal location of stalk and gland
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- **Surgical or traumatic stalk transection**
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- Permits build-up of neurosecretory granules along stump
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- [Hypothalamic lipoma (located at tuber cinereum)](/document/lipoma-brain/1bdb974e-8346-4730-9b1c-dea7b70b844d)
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- Posterior pituitary is not suppressed by fat saturation; lipoma is suppressed
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- ## Duplicated Pituitary Gland/Stalk
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- **Dilated infundibular recess of 3rd ventricle ("pseudoduplication")**
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- Simulates duplicated stalk but only 1 gland and 1 pituitary fossa
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- [Tuber cinereum hamartoma](/document/hypothalamic-hamartoma/7f85487f-9497-44a9-b884-b98e50d41018)
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- Round mass of 3rd ventricle floor but 1 midline pituitary stalk/gland
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# PATHOLOGY
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- ## General Features
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- ### Etiology
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- PPE: Genetic mutation → defective neuronal migration during embryogenesis
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- Adenohypophysis (anterior pituitary) grows up from stomodeal ectoderm (Rathke pouch)
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- Hypothalamic-releasing hormones reach adenohypophysis via infundibular portal system
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- Anterior pituitary dysfunction thought to be related to absent infundibulum
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- Neurohypophysis (posterior pituitary) grows down from diencephalic neuroectoderm, remains attached by stalk
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- Antidiuretic hormone and oxytocin transported to neurohypophysis via neurosecretory cells along infundibulum
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- DP: Congenital anomaly, presumed genetic duplication of stomodeal origin structures 2° to aberrant ventral induction
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- Theory: Duplication prechordal plate and tip of rostral notochord leads to duplicated pituitary primordium
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- ### Genetics
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- PPE: Mutations in genes encoding developmental transcription factors allow maldevelopment
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- *HESX1* (homeobox gene), *POU1F1* (PIT1), *PITX2*, *LHX3*, *LHX4*, *PROP1*, *SF1*, and *TBX19* (TPIT)
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- DP: Gene mutation unknown; may constitute polytopic field defect due to splitting of notochord
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- ### Associated abnormalities
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- DP
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- Midline tumors in oral, nasopharyngeal, palate
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- Epignathus, hamartomas, teratomas, dermoids, lipomas
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- Spinal anomalies include segmentation/fusion anomalies, schisms, hydromyelia, enteric cysts
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- Rib and cardiac anomalies, Pierre-Robin anomaly
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- **Both**: Common midline CNS anomalies
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- PPE
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- ± anomalies of structures formed at same time (anterior pituitary lobe, forebrain, eyes, olfactory bulbs)
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- ± lobar holoprosencephaly, septo-optic dysplasia, Joubert syndrome
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- DP
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- Callosal dysgenesis, Dandy-Walker spectrum, frontonasal dysplasia
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- Craniofacial clefting and duplication anomalies: Frontonasal dysplasia; clefts/duplication of skull base, face, mandible, nose, palate
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- Pituitary hypoplasia associated with Kallmann syndrome
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- ## Gross Pathologic & Surgical Features
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- PPE: Hypoplastic anterior lobe, stalk truncation or aplasia
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- Sella may be covered over with dura
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- DP: Tuberomammillary fusion, 2 normal glands/stalks
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- ## Microscopic Features
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- PPE: Ectopic pituitary cells in stalk or sphenoid bone
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- DP: Normal (but duplicated) pituitary glands, tuberomammillary fusion, incompletely migrated hypothalamic nuclear cells
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# CLINICAL ISSUES
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- ## Presentation
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- ### Most common signs/symptoms
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- PPE: Short stature
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- DP: Unsuspected finding on craniofacial imaging for other indications
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- ### Other signs/symptoms
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- PPE: Multiple pituitary hormone deficiencies common
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- DP: Rarely symptomatic from pituitary causes
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- ### Clinical profile
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- PPE: Short stature (growth hormone deficiency), ± multiple endocrine deficiencies
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- Peak growth hormone levels < 3 g/L more likely to have abnormal MR
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- ± anosmia, poor vision, seizures (cortical malformations)
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- Neonatal hypoglycemia or jaundice, micropenis, single central incisor
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- DP: ± facial midline anomalies, oral or nasal mass (hamartoma or teratoma)
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- Face: ± hypertelorism or frontonasal dysplasia
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- Craniocervical segmentation and fusion anomalies
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- Airway or oral obstruction from pharyngeal tumor
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- ## Demographics
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- ### Age
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- PPE: Early growth failure apparent in childhood
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- DP: Usually discovered in early infancy during imaging for complicated facial anomalies
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- ### Sex
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- PPE: M > F
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- DP: M < F
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- ### Ethnicity
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- None identified in either diagnosis
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- ### Epidemiology
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- PPE: Prevalence 1:4,000 to 1:20,000 births
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- DP: Extremely rare (reported in 20+ cases)
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- ## Natural History & Prognosis
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- PPE: Stable if no pituitary/hypothalamic crises; growth may be normal for a while
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- Severity and number of hormone deficiencies predicted by degree of stalk and gland hypoplasia
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- DP: Usually significant intracranial, upper airway, or craniocervical malformations (some lethal)
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- Clinical outcome unrelated to pituitary function
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- ## Treatment
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- Assess/treat endocrine malfunction
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# DIAGNOSTIC CHECKLIST
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- ## Consider
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- PPE: Assess optic and olfactory nerves, frontal cortex
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- DP: Oral tumors compromise airway patency
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- ## Image Interpretation Pearls
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- PPE/DP: Can miss findings/diagnosis if thick sections (MR) are used or osseous structures (bone CT) not evaluated
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