Transcript Congenital Pituitary Abns (NXPowerLite)

Congenital Abnormalities of the
Sellar and Parasellar Regions
Division of Neuroradiology
Department of Radiology
University of North Carolina at Chapel Hill
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
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)
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
• Rathke’s 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
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)
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
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
Embryology
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).
Sadler, T., Susceptible periods during embryogenesis of the heart and endocrine glands.
Environ Health Perspect, 2000; 108: 555
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
Embryology
• Regulation of pituitary embryogenesis involves
a cascade of genes expressed during the 4th
week of life in the diencephalon initiating
formation of Rathke‘s 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
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 children’s
appearance by two months of age
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
Abnormal Separation of
Ectoderm and Neuroectoderm
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
Transsphenoidal Encephalocele
A
B
Figure 3. Sagittal post-Gd T1 (A) and T2 (B) images show herniation of a CSFfilled 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).
Congenital Abnormalities
Development of the Hypothalamo-Pituitary Axis
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
Hypoplastic Pituitary Gland
A
B
Figure 4. Coronal (A) and sagittal (B) T1 images show small pituitary
gland and stalk.
Pituitary and Hypothalamic Hypoplasia
Figure 5. Sagittal T1 image shows hypoplastic pituitary gland (black
arrow), hypothalamus and optic chiasm (white arrow).
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: (septooptic
dysplasia,
lobar
holoprosencephaly,
olfactory bulb anomalies)
Ectopic Neurohypophysis
A
B
Figure 6. Pre- (A) and post-Gd (B) sagittal T1 images show “bright
spot” in tuber cinereum of the hypothalamus
Ectopic Neurohypophysis with Thin Stalk
Figure 7. Sagittal T1 image shows ectopic neurohypophysis (black arrow)
in tuber cinereum and hypoplastic pituitary stalk (white arrow).
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
Duplicated Pituitary Gland
A
B
Figure 8. Post–Gd coronal (A) and axial (B) T1 images
show two stalks (arrows), pituitary glands and sellae.
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
Tuber Cinereum Hamartoma
A
B
C
Figure 9. Post–Gd 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).
Tuber Cinereum Hamartoma
A
B
Figure 10. Post–Gd 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).
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
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).
Congenital Disorders
Development of the Adenohypophysis
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)
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. MarsotDupuch).
Rathke’s Cleft Cyst
• Non-neoplastic cyst arising from remnants
of squamous epithelium of Rathke’s cleft
• Non-enhancing non-calcified intra or suprasuprasellar cyst
• Variable cyst content: mucous (T1 bright)
serous (T1 dark) and possible blood
products (T2 dark)
Rathke’s 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 Rathke’s cleft cyst
Rathke’s Cleft Cyst
Figure 15. Axial T2 image shows intrasellar mass with fluid level (arrow) a
typical feature of Rathke’s cleft cyst; the differential diagnosis includes a
hemorrhagic pituitary adenoma.
Craniopharyngioma
• Benign dysontogenetic epithelial tumor
arising from cell remnants of Rathke’s pouch
• Complex
mass,
with
inhomogeneous
enhancement of solid components
• Calcifications: very common
• T1 signal varies with cyst contents
• Bimodal age distribution (5-15 y; > 50)
Craniopharyngioma
A
B
Figure 16. Sagittal post-Gd T1 (A) and coronal T2 (B) images show an
enhancing suprasellar mass (arrows) with complex appearance.
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).
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
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.
Miscellaneous
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
Dermoid
Figure 19. Sagittal T1 image shows a well-defined bright
midline suprasellar mass (arrows).
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
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.
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., Gray’s 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.