Congenital Abnormalities of the Sellar and Parasellar Regions

1
Congenital Abnormalities of the Sellar and
Parasellar Regions

• Division of Neuroradiology
• Department of Radiology
• University of North Carolina at Chapel Hill

2
Purpose

• To present the imaging appearances of congenital
  diseases arising in the sellar and suprasellar
  regions
• To demonstrate how the embryological correlations
  of the pituitary gland with the adjacent
  structures facilitate the correct interpretation
  of sellar and parasellar congenital abnormalities

3
Embryology

• The pituitary gland consists of two
  embryological and functionally distinct
  divisions
• Adenohypophysis (pars anterior, pars intermedia
  and pars tuberalis)
• Neurohypophysis (median eminence, infundibular
  stem and pars posterior)

4
Embryology

• Development of the pituitary gland begins in the
  4th week of life with inductive signals from the
  diencephalon initiating the formation of Rathke's
  pouch
• Rathkes pouch has been considered as a
  diverticulum of the epithelium lining of the
  stomodeum but recent evidence indicates it is a
  derivative of neural ectoderm from the anterior
  neural ridge

5
Embryology

• By the 8th week of life, the primitive
  adenohypophysis separates from the oral cavity
  and primitive pituitary cells undergo rapid
  proliferation with differentiation into
  specialized hormone lines
• Adenohypophysis consists of pars anterior or
  distalis, pars intermedia (rudimentary in humans)
  and pars tuberalis (along the stalk)

6
Embryology

• Neurohypophysis originates from a neuroectodermal
  evagination of tissue in the diencephalic floor
  which grows to the stomodeal roof. An extension
  of the 3rd ventricle (the infundibular recess),
  persists in the neuroectodermal diverticulum of
  the forebrain
• Neurohypophysis is divided into median eminence,
  infundibular stem and pars posterior

7
Embryology
Figure 1A. 6-week embryo shows the dual origin of
the gland from Rathke's pouch and from
diencephalic floor (infundibulum) (used with
permission).
Sadler, T., Susceptible periods during
embryogenesis of the heart and endocrine glands.
Environ Health Perspect, 2000 108 555
8
Figure 1B. Pituitary at 11 weeks of life. The
gland is formed and a cleft persists between pars
intermedia and pars anterior. The
craniopharyngeal canal closes and occasionally
the adenohypophysis remains in the nasopharynx
(used with permission).
Embryology
Sadler, T., Susceptible periods during
embryogenesis of the heart and endocrine glands.
Environ Health Perspect, 2000 108 555
9
Embryology
Figure 1C. Pituitary gland at 16 weeks of life.
The gland acquires an adult configuration and
the craniopharyngeal canal closes (used with
permission).
Sadler, T., Susceptible periods during
embryogenesis of the heart and endocrine glands.
Environ Health Perspect, 2000 108 555
10
Embryology

• Regulation of pituitary embryogenesis involves a
  cascade of genes expressed during the 4th week of
  life in the diencephalon initiating formation of
  Rathkes pouch and later a combined expression of
  multiple genes throughout the stomodeal
  epithelium required for morphogenesis of the
  pouch and proliferation and differentiation of
  hormone specific cells

11
Newborn Pituitary Gland

• In neonates the pars anterior and pars posterior
  are both uniformly bright on the T1 images
• At birth the pituitary gland may also be globular
  in shape
• This appearance likely reflects the hormonal
  surges that occur perinatally
• The signal intensity and size of the pituitary
  gland becomes similar to older childrens
  appearance by two months of age

12
Newborn Pituitary Gland
Figure 2. Sagittal non-contrast T1 image shows
pituitary gland at 5 days of age. Until 2 months
of age, the pituitary gland is uniformly bright
13
Abnormal Separation of Ectoderm and Neuroectoderm
14
Transsphenoidal Encephalocele

• It is an occult encephalocele characterized by
  a bone defect in ethmoid or sphenoid bone
• Usually diagnosed later than other forms of
  encephaloceles
• Hypothalamus, pituitary gland, 3rd ventricle,
  optic nerves and chiasm may be located in the
  encephalocele sac
• Typical clinical presentation nasal obstruction,
  difficulty feeding and failure to thrive

15
Transsphenoidal Encephalocele
A
B
Figure 3. Sagittal post-Gd T1 (A) and T2 (B)
images show herniation of a CSF-filled sac
(white arrows) through a bone defect in the body
of the sphenoid. The neurohypophysis (black
arrow) is also noted. Agenesis of the corpus
callosum (C/o of Dr. A. Rossi).
16
Congenital AbnormalitiesDevelopment of the
Hypothalamo-Pituitary Axis
17
Hypoplastic Pituitary Gland

• Pituitary hypoplasia is a congenital disorder
  involving the adenohypophysis, neurohypophysis
  and often the stalk
• Patients with pituitary hypoplasia survive with
  hormonal replacement but pituitary aplasia is
  incompatible with life
• Pituitary dwarfism due to deficiency of growth
  hormone is a common clinical presentation

18
Hypoplastic Pituitary Gland
A
B
Figure 4. Coronal (A) and sagittal (B) T1 images
show small pituitary gland and stalk.
19
Pituitary and Hypothalamic Hypoplasia
Figure 5. Sagittal T1 image shows hypoplastic
pituitary gland (black arrow), hypothalamus and
optic chiasm (white arrow).
20
Ectopic Neurohypophysis

• It is characterized by a bright spot along
  median eminence of hypothalamus or along stalk
  which may be tiny or absent
• Adenohypophysis and sella may be small
• Frequently associated with growth hormone
  deficiency (pituitary dwarfism)
• Associated adenohypophysis dysfunction may be
  related to absent infundibulum
• Associated midline CNS abnormalities
  (septo-optic dysplasia, lobar holoprosencephaly,
  olfactory bulb anomalies)

21
Ectopic Neurohypophysis
A
B
Figure 6. Pre- (A) and post-Gd (B) sagittal T1
images show bright spot in tuber cinereum of
the hypothalamus
22
Ectopic Neurohypophysis with Thin Stalk
Figure 7. Sagittal T1 image shows ectopic
neurohypophysis (black arrow) in tuber cinereum
and hypoplastic pituitary stalk (white arrow).
23
Duplicated Pituitary Gland

• Rare congenital disorder due to duplication of
  primitive stomodeal structures
• Two sellae, lateral stalks and glands are present
• Mammillary bodies are fused with tuber cinereum,
  thickening of 3rd ventricle floor (hamartoma?)
• Basilar artery shows lack of longitudinal fusion
• Anterior 3rd ventricle may be duplicated
• Possible association with CN I and II hypoplasia
• Pituitary-related symptoms are rare
• Associations craniofacial clefting, oral midline
  tumors, dysgenesis of corpus callosum,
  Dandy-Walker spectrum

24
Duplicated Pituitary Gland
A
B
Figure 8. PostGd coronal (A) and axial (B) T1
images show two stalks (arrows), pituitary glands
and sellae.
25
Tuber Cinereum Hamartoma

• It is a congenital malformation characterized by
  heterotopia of gray matter in the region of the
  mammillary bodies or tuber cinereum
• Round non-enhancing pedunculated or sessile mass,
  contiguous with tuber cinereum isointense to
  gray matter on T1 and slightly T2 bright
• Isosexual precocious puberty due to LHRH and/or
  gelastic seizures
• Common associations congenital facial/cerebral
  midline abnormalities, visceral anomalies,
  digital malformations
• Differential diagnosis hypothalamic astrocytoma,
  hystiocytosis, germ cell tumor

26
Tuber Cinereum Hamartoma
A B
C
Figure 9. PostGd T1 (A), T2 (B) sagittal, and
post-Gd T1 axial (C) images. A mass is seen
between the infundibulum and mammillary bodies,
hyperintense to gray matter on T2. The mass
appears similar to the brain parenchyma on T1
and shows no enhancement (courtesy of Dr. A.
Osborn).
27
Tuber Cinereum Hamartoma
A
B
Figure 10. PostGd sagittal T1 (A) and T2 (B)
images show a large tuber cinereum hamartoma that
is T1 isointense and T2 bright (courtesy of Dr.
A. Osborn).
28
Optic Infundibular Hypoplasia

• Disorder of midline prosencephalic development
  (6th weeks of life)
• Overlaps with septo-optic dysplasia but septum
  pellucidum is present
• Optic chiasm/optic nerves are hypoplastic
• Pituitary hypoplasia, thin stalk, ectopic
  neurohypophysis may be present

29
Optic Infundibular Hypoplasia
A
B
C
Figure 11. Sagittal T1 (A), coronal T2 (B) and T1
(C). A Hypoplastic pituitary gland, stalk, optic
chiasm and hypothalamus. B Hypoplastic optic
nerves. C Ectopic neurohypophysis (arrow).
30
Congenital Disorders Development of the
Adenohypophysis
31
Persistent Craniopharyngeal Canal
A
B
Figure 12. Sagittal T1 (A) and coronal T1 (B)
images. The craniopharyngeal canal is patent. The
adenohypophysis is within the canal (arrow) and
extends into the nasopharynx (arrowhead) (C/o of
Dr. M. Michel)
32
Persistent Craniopharyngeal Canal
A
B
Figure 13. Sagittal T1 MR (A) and axial CT (B)
images. A The adenohypophysis (arrow) is in a
persistent craniopharyngeal canal. B Shows
persistence of a craniopharingeal canal
(arrowhead) (C/o Dr. K. Marsot-Dupuch).
33
Rathkes Cleft Cyst

• Non-neoplastic cyst arising from remnants of
  squamous epithelium of Rathkes cleft
• Non-enhancing non-calcified intra or
  supra-suprasellar cyst
• Variable cyst content mucous (T1 bright) serous
  (T1 dark) and possible blood products (T2 dark)

34
Rathkes Cleft Cyst
A
B
Figure 14. Pre- (A) and post-Gd (B) T1 weighted
images show an intrasellar mass (black arrow)
that is bright compared to normal pituitary gland
(white arrow). Location (middle 1/3 of gland) and
signal intensity strongly suggest a Rathkes
cleft cyst
35
Rathkes Cleft Cyst
Figure 15. Axial T2 image shows intrasellar mass
with fluid level (arrow) a typical feature of
Rathkes cleft cyst the differential diagnosis
includes a hemorrhagic pituitary adenoma.
36
Craniopharyngioma

• Benign dysontogenetic epithelial tumor arising
  from cell remnants of Rathkes pouch
• Complex mass, with inhomogeneous enhancement of
  solid components
• Calcifications very common
• T1 signal varies with cyst contents
• Bimodal age distribution (5-15 y gt 50)

37
Craniopharyngioma
A
B
Figure 16. Sagittal post-Gd T1 (A) and coronal T2
(B) images show an enhancing suprasellar mass
(arrows) with complex appearance.
38
Craniopharyngioma
A
B
Figure 17. Coronal (A) and sagittal (B) post-Gd
T1 images show a suprasellar cystic mass (white
arrows). A solid enhancing nodule is noted (black
arrow) and the rim also enhances (small white
arrows).
39
Pars Intermedia Cyst

• These cysts arise in the pars intermedia of the
  adenohypophysis which is rudimentary in humans
• They are usually less than 3 mm in diameter
• They are located between the pars anterior and
  pars posterior

40
Pars Intermedia Cyst
A C
B
Figure 18. Sagittal pre- (A) and post-Gd (B) T1
images and (C) axial T2 image show nonenhancing
cyst (arrows) between the pars anterior and pars
posterior.
41
Miscellaneous
42
Dermoid

• Intracranial dermoids are ectodermal inclusion
  cysts that originate from midline inclusion of
  surface ectoderm during the 3rd-5th weeks of life
  at the time of closure of the neural tube
• Common intracranial locations frontonasal,
  sellar and parasellar regions, posterior fossa
  and ventricles
• Dermoids are T1 bright due to presence of lipids
  and cholesterols and may rupture with spreading
  of fat droplets along the CSF containing spaces
  resulting in aseptic meningitis

43
Dermoid
Figure 19. Sagittal T1 image shows a well-defined
bright midline suprasellar mass (arrows).
44
Teratoma

• Teratomas are composed of tissues from the three
  embryonic germ layers
• The majority of teratomas are supratentorial in
  the region of the optic chiasm and in the pineal
  gland
• They are midline tumors containing fat, soft
  tissue and calcifications
• Classified as mature, immature and malignant
• Occasionally they present in newborns as
  holocranial tumors

45
Teratoma
A
B
Figure 20. Sagittal non-contrast T1 (A) and axial
fat-suppressed T2 (B) images show a heterogeneous
suprasellar mass (arrows) due to presence of
calcifications and fat.
46
References
Barkovich, A., Pediatric Neuroimaging. 3rd
edition ed. 2000, New York Raven Press. Chen,
C., D. David, and A. Hanieh, Morning glory
syndrome and basal encephalocele. Childs Nerv
Syst, 2004(20) p. 87-90. Chong, B. and T.
Newton, Hypothalamic and pituitary pathology. The
Radiology Clinics of North America, 1993. 31(5)
p. 1147-1183. Dietrich, R., et al., Normal MR
appearance of the pituitary gland in the first
two years of life. AJNR, 1995. 16 p.
1413-1419. Gray, H., Grays Anatomy. 37th edition
ed. 1989, New York, Churchill Livingstone.
Osborn, A., Diagnostic Imaging. Brain. 2004,
Salt Lake City Amirsys. Sadler, T., Susceptible
periods during embryogenesis of the heart and
endocrine glands. Environ Health Perspect., 2000.
108 p. 555-561. Shroff, M., et al., Basilar
artery duplication associated with pituitary
duplication a new finding. AJNR, 2003(24) p.
956-961.