1. Imaging of the Pediatric Hypothalamic-Pituitary Axis: How Embryology Sheds Light on Pathology ASNR 2015 Annual Meeting Jayant Boolchand, MD Bruno P Soares, MD Abstract No: eEdE-171 Submission Number:275 Department of Radiology and Imaging Sciences Division of Neuroradiology

2. Disclosures The authors have no relevant disclosures.

3. Pituitary embryology Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556. Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244- 015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Adenohypophysis  Derives from Rathke’s pouch, an ectodermal outpouching of stomodeum and infundibulum, at approximately 24 days gestation  Rathke’s pouch consists of: anterior wall, a precursor of the anterior lobe and pars tuberalis; posterior wall, which develops into the pars intermedia; and a central cleft  Course and development of Rathke’s pouch:  Originates rostral to the oropharyngeal membrane  Migrates dorsally via a canal in the body of the sphenoid bone  Separates from the oral cavity in the 7 th week of life  Craniopharyngeal canal regresses and normally becomes obliterated by six months  Primitive pituitary cells undergo differentiation and produce hormones (TSH, GH, prolactin, LH, FSH)

4. Pituitary embryology Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556. Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841 Hamilton BE, Salzman KL, Osborn AG. Anatomic and pathologic spectrum of pituitary infundibulum lesions. AJR Am J Roentgenol. 2007 Mar;188(3):W223-32. PubMed PMID: 17312027.  Adenohypophysis  Consists of:  Pars tuberalis – surrounds the infundibulum  Pars intermedia – portion of midline cells in Rathke’s pouch; separates adenohypophysis from neurohypophysis  Pars distalis – enlarges and becomes the anterior lobe; extends superiorly along the anterior aspect of infundibulum  Neurohypophysis  As Rathke’s pouch is developing, the posterior lobe originates from neuroectodermal evagination of tissue from the hypothalamus/floor of the third ventricle/diencephalon  Functionally composed of: posterior lobe, the infundibulum and the medial eminence of the hypothalamus  Secretes oxytocin and vasopressin synthetized in the hypothalamus

5. Pituitary embryology Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841 Hamilton BE, Salzman KL, Osborn AG. Anatomic and pathologic spectrum of pituitary infundibulum lesions. AJR Am J Roentgenol. 2007 Mar;188(3):W223-32. PubMed PMID: 17312027.  Pituitary Stalk  Variably hollow tube that arises from the ventromedial hypothalamus and is contiguous with the infundibular recess of the third ventricle  Though the most distal aspect of the infundibulum differentiates into the neurohypophysis, the pituitary stalk has components of both the anterior and posterior lobes, which explains the presence of adenomas arising in the stalk  Pars tuberalis encircles the infundibulum as it enters the adenohypophysis

6. Normal development of the pituitary gland Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.

7. Normal pituitary anatomy Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.

8. Normal pituitary anatomy Delman BN. Imaging of pediatric pituitary abnormalities. Endocrinol Metab Clin North Am. 2009 Dec;38(4):673-98. doi: 10.1016/j.ecl.2009.09.001. Review. PubMed PMID: 19944287.

9. Normal pituitary anatomy Delman BN. Imaging of pediatric pituitary abnormalities. Endocrinol Metab Clin North Am. 2009 Dec;38(4):673-98. doi: 10.1016/j.ecl.2009.09.001. Review. PubMed PMID: 19944287.

10. Imaging appearance of neonatal gland Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556. Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841 Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401- 5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Adenohypophysis  In newborns T1 hyperintense, gradually becomes T1 isointense to the pons by 6-8 weeks  Signal intensity reflects the newborn’s postnatal age and not the gestational age at birth  At birth, the gland is physiologically enlarged with a concave superior margin; then flattens, and takes a more globular shape  Height of gland decreases in the first 8 weeks  In preterm infants the gland is taller than in normal-term infants, thought to be due to reduced IGF-1 and higher levels of growth hormone in premature infants  Neurohypophysis  T1 hyperintense  Infundibulum  Usually midline, but may insert off center in up to 46% of patients  Should be no larger than 2.6 mm  May be seen by MRI after fetus is 25 weeks

11. Normal T1 hyperintense appearance of the neonatal gland

12. Normal globular appearance of the neonatal gland

13. Imaging appearance of childhood and adolescent gland Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841  Experiences linear and constant growth, reaching a height of approximately 6 mm  At puberty, the gland enlarges, and tends to be slightly larger in height in girls (10 mm) than in boys (8 mm)  In girls, it is not uncommon for the gland to convex superiorly; the size of the gland may also vary with the menses, becoming slightly larger just before menstruation; generally does not measure more than 10 to 12 mm in height

14. Normal physiologic prepubertal pituitary hyperplasia

15. Gland during pregnancy Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841.  Increase in gland size from 30-100%, particularly in the third trimester; upwardly convex border  Occasionally, the adenohypophysis becomes somewhat T1 bright  Reaches it maximum size a few days after birth and gradually returns to normal (regardless of breast-feeding choices)  May cause bitemporal hemianopsia  Histologically, the number of lactotrophs increases until it compromises nearly 60% of total cell population of the gland

16. Normal postpartum gland

17. Imaging appearance of pituitary infundibulum Hamilton BE, Salzman KL, Osborn AG. Anatomic and pathologic spectrum of pituitary infundibulum lesions. AJR Am J Roentgenol. 2007 Mar;188(3):W223-32. PubMed PMID: 17312027. Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841.  Tapers from superior to inferior  3.45 +/- 0.56 mm at the level of the optic chiasm and narrows to 1.91 +/- 0.4 mm at its insertion  Signal intensity on T1 usually less than optic chiasm  Lacks blood brain barrier and thus normally enhances  Deviation is common and does not necessarily imply underlying disease, especially in cases where the floor of the sella may slope normally to one side  Insertion of intersphenoid septum at the floor of the sella may result in artifacts that may be confusing. Magnetic susceptibility-induced signal loss in the gland at the level of the septal insertion must not be confused with an adenoma

18. Imaging appearance of the neurohypophysis Castillo M. Pituitary gland: development, normal appearances, and magnetic resonance imaging protocols. Top Magn Reson Imaging. 2005 Jul;16(4):259-68. Review. PubMed PMID: 16785841.  Etiology of increased T1 signal (“bright spot”) is controversial– believed to be related to vasopressin neurosecretory granules (neurophysin); lipoid bodies in pituicytes; presence of phospholipid vesicles  If the stalk is anatomically and functionally normal, an intrasellar bright spot is present. Functional damage to the stalk results in absence of the bright spot  Dehydration results in a smaller bright spot, due to active secretion of ADH  Overhydration results in a larger bright spot, due to accumulation of the hormone in the posterior lobe

19. Persistent craniopharyngeal canal Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Skull base midline defect at the level of the sphenoid, connecting the floor of the sella with the superior wall of the nasopharynx; usually measures less than 1.5 cm  Lack of involution of the craniopharyngeal canal can contain pituitary tissue  Pathway of Rathke’s pouch is the craniopharyngeal canal, which progressively normally involutes by 6-7 weeks of gestation  In cases where the canal persists, can be associated trans-sphenoidal meningoencephaloceles, ectopic pituitary tissue, sphenoid teratoma and infrasellar craniopharyngiomas  Insult during 42-45 days of gestational life can lead to persistence of canal

20. Ectopic pituitary tissue within a persistent craniopharyngeal canal

22. Transsphenoidal encephalocele Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Wide spectrum of congenital abnormalities affects the skull base in the region of the sella turcica, ranging from persistent craniopharyngeal canal to transsphenoidal and sphenoethmoidal cephalocele  Congenital malformation involving the lack of separation of neuroectoderm from surface ectoderm results in failure of localized bone formation or from failed fusion of ossification centers  Herniation of CSF filled sac containing neural and vascular tissue  Content may include the hypothalamus, pituitary gland, third ventricle, anterior cerebral arteries, optic nerves and chiasm  May present with feeding and nasal obstruction in the first year, and potential for CSF leaks and meningitis  Associated with agenesis of the corpus callosum, hypertelorism, craniofacial midline defects, dysfunction of the hypothalamopituitary axis, and optic pathway abnormalities

23. Ectopic neurohypophysis Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  When ectopic usually located along the ventral aspect of the hypothalamus (median eminence)  Absent, truncated, or thread-like pituitary stalk; small adenohypophysis  Almost always accompanied by decreased hypothalamic – pituitary function  Most common imaging finding in children with growth retardation  Can be isolated finding or associated with other midline anomalies, such as lobar holoprosencephaly, septic-optic dysplasia, pituitary dwarfism, delayed skeletal maturation, Kallman syndrome, dysgenesis of the corpus callosum  May also develop following trauma  If stalk transected at the proximal aspect, axons from the hypothalamus may reorganize to store and release vasopressin

24. Ectopic neurohypophysis

25. Rathke cleft cyst Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556. Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Nonneoplastic cysts arising from failure of obliteration of the embryonic cleft of Rathke pouch; arise from epithelial rests of the craniopharyngeal canal; usually between the anterior and posterior lobes in the region of the pars intermedia  Walls of cyst lined with columnar or cuboidal epithelium; contains fluid and variable amounts of protein, mucopolysaccharides and/or cholesterol  May be intrasellar only, but most are intra- and suprasellar (87%)  2-3 times more common in women  May be symptomatically related to compression of adjacent structures  Most are stable in size, some may disappear spontaneously; may slowly increase in size because of imbalance between secretion and reabsorption of cyst contents  Cyst growth and/or intracystic hemorrhage or infection can occasionally cause visual disturbances, headaches, diabetes inspidus, or pituitary dysfunction

26. Rathke cleft cyst Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Intermediate or high signal intensity on T1 and T2; signal characteristics vary based on protein content  Thin peripheral enhancement of the wall; no central or solid enhancement  Intracystic nodules – no enhancement; low signal intensity on T2  Mucinous mixed cholesterol and protein  ADC increased compared to cystic components of craniopharyngiomas and hemorrhagic pituitary adenomas  May have mass effect on the infundibulum, pituitary gland or infundibulum  Pars intermedia cysts – less than 3 mm, asymptomatic, incidental and difficult to distinguish from Rathke cleft cyst

27. Sellar/Suprasellar Rathke cleft cyst

28. Pars intermedia cyst

29. Craniopharyngioma Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  50% of pediatric suprasellar tumors; 3% of all intracranial tumors  Histologically benign, locally aggressive; occur in bimodal distribution in children ( 40 years)  Two types: adamantinomatous type (all age groups) and papillary type (almost always adults)  Suprasellar component in 95% of cases  Extension in middle cranial fossae in up to 30% of cases  Frequently contain proteinaceous fluid (bright on T1), cysts, lipid components and calcifications

30. Craniopharyngioma Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Intermediate and/or high signal on T1 and T2 with or without nodular or rim enhancement  Adamantinomatous (bimodal in children and adults)  Hyperintense cystic components (T1), lobulated shape and vascular encasement  Squamous – papillary subtype (adults)  Hypointense cysts (T1), enhancing solid components- results in flip flop of T1 signal between cystic and solid portions comparing pre and post imaging  Mets may occur via tumor transplantation during surgery or CSF dissemination

31. Craniopharyngioma Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Two hypotheses for development:  Embryogenetic theory: adamantinomatous subtype comes from remnants of Rathke pouch or craniopharyngeal duct – the duct and pouch are derived from the stomadeum, which form (among other things) teeth primordia  Metaplastic theory: squamous papillary subtype occurs from neoplasia of squamous cell rests – remnants of the part of the stomadeum that contribute to the buccal mucosa  Classified by size and relationship to the optic chiasm  Sellar CP  Prechiasmatic suprasellar CP  Retrochiasmatic CP  Giant CP (anterior, middle, or posterior cranial fossae)  Neurosurgeon needs to be aware of relationship to hypothalamus, third ventricle and arteries of the Circle of Willis

32. Craniopharyngioma  50% suprasellar tumors  Adamantinous  90% have Ca++  90% cystic  90% enhance  May expand sella! (arises along path of Rathke’s pouch)

33. Pituitary hyperplasia Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  May enlarge from stimulation by the hypothalamus and mimic true mass  Homogeneous appearance on all pulse sequences  May be physiological – can reach 10 mm or even higher, especially in females  Thyrotrophs will enlarge in the setting of chronic hypothyroidism  Somatotrophs will enlarge in the setting of pheochromocytomas  Lactotrophs will enlarge during pregnancy

34. Empty sella Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595. Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Pituitary gland measuring 2 mm or less  Can result from weakened or fenestrated diaphragma sella allowing CSF pulsations to flatten the pituitary gland  Associated with elevated intracranial pressure, a posteriorly placed optic chiasm, and considered a normal variant or termed “primary empty sella turcica” in the absence of surgery, radiation therapy or medically treated intrasellar tumor  CSF occupying more than half of the sella  Found in just over 1% of patients but in almost 11% of those with possible hypothalamic – pituitary abnormalities  Possible etiologies: congenital abnormalities as well as adverse perinatal events

35. Agenesis and hypoplasia of the pituitary gland Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842.  Rare  Newborn with jaundice, metabolic acidosis, liver dysfunction, adrenal and thyroid insufficiency, severe hypoglycemia  Associated with developmental disorders of the midline forebrain and craniofacial structures  Can survive with hormone replacement therapy

36. Pituitary dwarfism Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842.  Heterogeneous group of diseases caused by isolated GH deficiency or deficiency of multiple pituitary hormones  Imaging does not always correlate  Normal to hypoplastic to absent  Pathogenesis of MRI abnormalities is uncertain  Higher frequency in difficult deliveries (breech, perinatal asphyxia, low Apgar)  Traumatic transection of the pituitary stalk, hypoxic injury of the hypothalamus could result in hypoplasia of adenohypophysis, whereas regenerated hypothalamic axons would reconstitute the neurohypophysis in a more proximal insult  Genetic causes of an abnormal interaction between the Rathke pouch and the diencephalon have been postulated

37. Duplicated pituitary gland Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842.  Very rare  Frequently accompanied by duplication of stalk  Enlargement of the hypothalamus with fusion of the mammillary bodies and tuber cinereum or hamartoma of the tuber cinereum can be seen  May result from abnormal splitting of the anterior end of the notochord and prechordal plate due to teratogenic factors during early embryogenesis  May represent a variant of the median cleft face syndrome

38. Duplicated pituitary gland Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842.  Associated with:  Dysgenesis of the corpus callosum  Duplication of the anterior third ventricle  Absence of the olfactory bulbs and tracts  Duplication of the optic chiasm, hypothalamic hamartoma  Hypertelorism  Fenestration or complete duplication of the basilar artery  Dandy-Walker spectrum  Cleft of the basisphenoid  Craniofacial clefting, oral midline tumors (teratomas and dermoids)  Malformations of the spine (diplomyelia, Klippel-Feil anomaly, and clefting of cervical posterior elements, and duplicated cervical or thoracic vertebral bodies

39. Duplicated pituitary gland  Duplicated pituitary glands  Duplicated pituitary stalks  Hypothalamic hamartoma

40. Hypothalamic hamartoma Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Li CD, Luo SQ, Tang J, Jia G, Ma ZY, Zhang YQ. Classification of hypothalamic hamartoma and prognostic factors for surgical outcome. Acta Neurol Scand. 2014 Jul;130(1):18-26. doi: 10.1111/ane.12209. Epub 2014 Jan 2. PubMed PMID: 24382157. Shields R, Mangla R, Almast J, Meyers S. Magnetic resonance imaging of sellar and juxtasellar abnormalities in the paediatric population: an imaging review. Insights Imaging. 2015 Apr;6(2):241-60. doi: 10.1007/s13244-015-0401-5. Epub 2015 Mar 21. PubMed PMID: 25794595.  Congenital developmental non-neoplastic grey matter heterotopia involving the tuber cinereum, inferior hypothalamus and/or mammillary bodies which are composed of small neuronal cells within a neutrophil-like stroma and scattered fibrillary astrocytes  Nonenhancing hypothalamic mass contiguous with the tuber cinerum  Sessile or pedunculated  Large sessile lesions  seizures  Small pedunculated lesions  central precocious puberty  Mass located between mammillary bodies and infindibulum  On MR spectroscopy, there may be an elevated myoinositol peak

41. Hypothalamic Hamartoma  Sessile or Pedunculated  More common in boys  Associated with: Gelastic Seizures or Precocious Puberty

42. Hypothalamic Hamartoma

43. Septo-optic dysplasia Spampinato MV, Castillo M. Congenital pathology of the pituitary gland and parasellar region. Top Magn Reson Imaging. 2005 Jul;16(4):269-76. Review. PubMed PMID: 16785842. Pediatric Neuroimaging. A. James Barkovich, Charles Raybaud. Edition 5. Lippincott Williams & Wilkins, 2012  Hypoplasia of the optic nerves, hypoplasia or absence of the septum pellucidum, and in two thirds of cases hypothalamic-pituitary dysfunction  Squared appearance of the frontal horns of the lateral ventricles and low position of the fornices on sagittal images  Ectopia of the posterior pituitary lobe and thin infundibulum

44. Septo-optic dysplasia  Hypoplasic anterior pituitary, pituitary stalk, optic chiasm, hypothalamus  Ectopic neurohypophysis  Absent septum pellucidum

45. Germ cell tumors Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Divided into germinomas and nongerminomatous germ cell tumors (70%)  Pineal region most common in males  Suprasellar region most common females  In the suprasellar cistern, most commonly centered in the stalk, with or without involvement of the hypothalamus  Presence of basal ganglia infiltration in the setting of abnormal thickening of the infundibulum and hypothalamus is characteristic  Variable signal characteristics; solid components enhance  T2 signal of solid components is usually iso- to hypointense compared to gray matter

46. Germ cell tumor Suprasellar and Pineal 5-10% Synchronous suprasellar and pineal involvement

47. Germ cell tumor  High risk of CSF spread: MRI of entire neuroaxis  Isolated Diabetes Insipidus: Suspect stalk involvement

48. Infundibular Lesions Pediatric Neuroimaging. A. James Barkovich, Charles Raybaud. Edition 5. Lippincott Williams & Wilkins, 2012 Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Classically present with diabetes inspidus  Diabetes insipidus occurs due to dysfunction of supraoptic or paraventricular nuclei of the hypothalamus. Infiltration of these nuclei can occur at a time when the infundibulum is still normal in size.  At the time a child presents with diabetes insipidus, a pituitary stalk lesion such as a germ cell tumor, granuloma or lymphocytic infiltration may not be visible yet by imaging, and in such patients repeat imaging should be obtained in 3 to 6 months and, if still negative, a second repeat examination should be obtained.  Three most common etiologies:  Langerhans histiocytosis (LCH)  Germ cell tumor (GCT)  Lymphocytic hypophysitis  Isolated thickening:  Sarcoidosis  Granulomatous infections, such as TB

49. Infundibular mass differential  Germinoma  Lymphocytic hypophysitis  Langerhans cell histiocytosis  Adenoma or nonadenomatous pituitary tumors  Granulomatous disease (sarcoid, wegner granulomatosis, tuberculosis)  Lymphoma  Metastatic disease  Other infiltration disease: Erdheim-Chester, Rosai Dorfman

50. Langerhans cell histiocytosis Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  LCH involves CNS in 4% of cases  In nearly all cases of LCH, the normal T1 hyperintensity of the neurohypophysis is absent  Hypothalamus and infundibulum are infiltrated in up to 20% (most common location in CNS)  When only neurohypophysis and infundibulum involved there is classically thickening of the pituitary stalk greater than 3.5 mm with loss of the pituitary bright spot  When entire gland is involved, diffuse inflammatory changes may be present which may involve optic chiasm or cavernous sinuses  Multiple CNS findings have been described:  White and gray matter lesions  Demyelination  Calvarial lesions  Partially empty sella  Extraparenchymal masses  Cerebellar degeneration

51. Thickening of the pituitary stalk in LCH

52. Lymphocytic hypophysitis Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Classified by anatomical location  Adenophyophysis  Infundibulum  Neurohypophysis  When infundibulum and neurohypophysis are involved diabetes insipidus is the most common symptom  In children – 50% of cases involve anterior and posterior pituitary lobes

53. Sarcoidosis Schroeder JW, Vezina LG. Pediatric sellar and suprasellar lesions. Pediatr Radiol. 2011 Mar;41(3):287-98; quiz 404-5. doi: 10.1007/s00247-010-1968-0. Epub 2011 Jan 26. Review. PubMed PMID: 21267556.  Prevalence in children is unknown  Prepubertal children with neurosarcoid may demonstrate seizure and hypothalamic dysfunction

54. Thickening of the pituitary stalk in sarcoidosis

55. Conclusions  The normal neonatal, pubertal and young adult pituitary gland have their own distinct appearances that should not be confused with congenital pathology  Knowledge of normal embryology of the pituitary gland, particularly the development of adenohypophysis from the Rathke pouch and of the neurohypophysis from the diencephalon, is central to the understanding of congenital pathology  When a child presents with diabetes insipidus, a pituitary stalk lesion may not be visible yet by imaging, and in such patients repeat imaging should be obtained in 3 to 6 months and, if still negative, a second repeat examination should be obtained  Interpretation of imaging features of acquired disorders also is enhanced by grasping basic concepts of hypothalamic-pituitary axis embryology and function