Pituitary Region Tumours: Not Always An Adenoma

Transcription

1 Pituitary Region Tumours: Not Always An Adenoma Poster No: C-0944 Congress: ECR 2014 Type: Educational Exhibit Authors: C W Oh, F Gaillard, Y D Weerakkody ; Melbourne/AU, Perth/AU Keywords: CNS, Neuroradiology brain, MR, Diagnostic procedure, Neoplasia DOI: /ecr2014/C-0944 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations wwwmyesrorg Page 1 of 33

2 Learning objectives At the end of reading this pictorial essay, we anticipate the reader would be able to illustrate the anatomy of the pituitary region on MRI brain imaging review the spectrum of neoplastic and non-neoplastic pathologies that can arise in the pituitary region discuss the incidence, clinical presentation and MRI features of these conditions Page 2 of 33

3 Background Magnetic resonance imaging is the gold standard imaging modality for evaluation of pituitary region lesions There are many tumours that can arise in this region and they 1 represent around 10-15% of all brain tumours 1 A pituitary adenoma is the most common of these tumours Due to its high prevalence rate and classical radiographic appearances, it is often not difficult for a radiologist to diagnose a pituitary adenoma on MRI As pitutiary adenomas can have a variety of appearances, they are often considered a likely diagnosis for a pituitary region tumour, even when appearances are atypical However as many other tumours and tumour like conditions in the pituitary region are encountered, familiarity with these are crucial if a confident pre-operative diagnosis is to be made Page 3 of 33

4 Findings and procedure details Anatomy The pituitary gland is a vital endocrine structure It consists of an anterior lobe (adenohypophysis), an intermediate lobe and a posterior lobe (neurohypophysis) It is connected to the hypothalamus via the infundibulum, which is located posterior to the 2 optic chiasm On MRI, the anterior lobe normally appears T1 isointense and enhances vividly with contrast as a result of its rich vascular supply The intermediate lobe is often hypointense on post contrast T1 image while the posterior lobe is T1 hyperintense in the 3 majority of the population The pituitary gland is located within the sella turcica (which is a depression within the sphenoid bone) Anatomical relations of the sella turcica are Fig 2 on page 14) 2 (Fig 1 on page 14 and Anterior: tuberculum sellae and anterior clinoid process Posterior: dorsum sellae and posterior clinoid process Lateral: cavernous sinuses (with their contents) Roof: diaphragm sellae (with optic chiasm above it) Floor: thin layer of sphenoid bone (with the sphenoid sinus below it) Pathological spectrum of pituitary lesions A variety of pathologies can occur in the pituitary region and this in part reflects the complex anatomical structure of this area They can range from being neoplastic, infectious, inflammatory, developmental and vascular A summary of this pathological spectrum is listed below Pathological spectrum of pituitary lesions Neoplastic Pituitary adenoma* Craniopharyngioma* Meningioma* Germinoma* Optic chiasmatic-hypothalamic glioma Teratoma* Page 4 of 33

5 Pituitary metastasis* Sphenoid sinus metastasis* Lymphoma* Chordoma Pituitary choristoma Infundibuloma Dermoids and epidermoid tumours Schwannoma Infectious and inflammatory Sarcoidosis Pituitary abscess Lymphocytic hypophysitis* Tuberculosis Vascular Aneurysm* Developmental Rathke's cleft cyst* Arachnoid cyst Ectopic posterior lobe Others Lipoma* Pituitary apoplexy Langerhans cell histiocytosis Hypothalamic hamartoma Empty sella *Conditions that will be discussed in this poster Pituitary adenoma Pituitary adenomas represent approximately 10% of all brain tumours and 30-50% of 3 pituitary region masses They are commonly encountered in adults and their peak 4 incidence is between 20 and 40 years of age Pituitary adenomas can be grouped in a number of ways Most commonly they are categorised arbitrarily according to size or according to hormonal activity Page 5 of 33

6 Type of adenoma (based on size) 4 Pituitary microadenoma ( < 10mm) Pituitary macroadenoma ( > 10mm) Type of adenoma (based on hormonal activity) 7 Prolactin (PRL)-secreting adenoma (most common: seen in up to 50% of hormonally active adenomas ) Growth hormone(gh)-secreting adenoma Mixed GH- and PRL-secreting adenoma Adrenocorticotropic hormone(acth)-secreting adenoma Thyroid-stimulating hormone(tsh)-secreting adenoma Gonadotropin-secreting adenoma Null cell adenoma 4 The clinical presentation of pituitary adenomas depends on their functional state and size Functional tumours (particularly ACTH secreting tumours), typically present as small lesions and clinically manifest with hormonal imbalances (eg Cushing's disease in the case of ACTH secretion) Non-functional tumours and prolactinomas (which have relatively subtle symptoms) typically do not present until they are much larger and tend to present with compressive effects on adjacent structures, most notably the optic chiasm 4 resulting in a bitemporal hemianopia Pituitary microadenoma (Fig 3 on page 15) Pituitary microadenomas are less common than macroadenomas but may pose a greater diagnostic challenge due to their small sizes and diverse clinical presentations Pituitary imaging requires specific sequences (thin slice, small field of view and dynamic contrast acquisitions) Pituitary microadenomas commonly manifest with hormonal imbalances 4 rather than with symptoms due to mass effect Radiographic features The key sequence in identifying microadenomas is the dynamic contrast enhanced T1 sequence Microadenomas appear as a region of hypo5,9 enhancement relative to the rest of the gland Other sequences demonstrate variable signal characteristics: T1-weighted sequences: hypointense to isointense compared to adjacent pituitary gland Can be T1 hyperintense if complicated by intratumoural haemorrhage 4,8 4 T2-weighted sequences: hyperintense Page 6 of 33

7 T1-weighted sequences with contrast: delayed images can range from being hypointense (most common) to isointense to hyperintense 8-10 Pituitary macroadenoma (Fig 4 on page 16) 3 Pituitary macroadenomas are twice as common as microadenomas They most commonly present with symptoms related to local mass effect Pituitary macroadenomas are normally well delineated and have slow growth rates and thus remodel the pituitary 3 fossa They can extend and invade: The optic chiasm superiorly The sphenoid sinus inferiorly The cavernous sinus laterally Radiographic features A "snowman" or "figure 8" appearance may be seen as the tumour extends through the diaphragm sellae They can present with cystic components (hypointense to hyperintense on 3 4,10 T1-weighted sequences and hyperintense on T2-weighted sequences) They may also have haemorrhagic components (which are hyperintense on both T1 and T2-weighted sequences depending on the age of blood products) Assessing cavernous sinus invasion can be challenging Using the percentage of total encasement of the intracavernous ICA by the adenoma has shown to be helpful in this situation If more than 67% encasement of the intracavernous ICA is seen, it can be intrepreted as being almost certain that cavernous sinus invasion has occurred On the contrary, if less than 25% encasement of the intracavernous ICA is seen, cavernous sinus 6 invasion is considered very unlikely Meningioma (Fig 5 on page 17) Meningiomas represent 15% of all brain tumours Up to 10% of all meningiomas occur 3 in the sellar region In terms of overall suprasellar occurrence, meningiomas are the 4 second commonest tumour amongst adults Cavernous sinus meningiomas are also not uncommon Page 7 of 33

8 Visual disturbances are the commonest of clinical presentations due to compressive effects on the optic nerves, the optic chiasm and optic tracts Oculomotor nerves may also be affected occasionally 3-4,8 Radiographic features T1-weighted sequences with contrast: meningiomas typically enhance homogenously and intensely, whereas adenomas tend to have less vivid 8,13 enhancement T2 weighted sequences: meninigomas usually are iso intense to cortex, whereas macroadenomas are usually hyperintense A dural tail sign (although not specific) can be seen in up to 70% of 14 meningiomas Unequal narrowing of the siphon of the internal carotid artery is helpful when the cavernous sinus is involved, as macroadenomas tend not to narrow 4 vessels Craniopharyngioma (Fig 6 on page 18 and Fig 7 on page 19) Craniopharyngiomas are benign slow growing tumours derived from the Rathke's pouch 4 They represent around 21-46% of all intracranial tumours They have a bimodal th 10 age presentation: ie at around 5-10 years of age and at the 6 decade of life Although craniopharygiomas mostly occur in the suprasellar region, they are capable of invading the optic chiasm or midbrain which can then cause obstructive hydrocephalus Their common clinical presentations include headaches, endocrine problems and visual 3 disturbances such as bitemporal hemianopsia or inferior quandrantopia Histologically, they can be classified into: ,11 Adamantinomatous type (mainly seen in children) Papillary type (mainly seen in adults) Radiographic features Adamantinomatous type craniopharyngiomas classically have both cystic and solid components Their cystic fluid resembles "motor oil" in viscosity 3 due to high protein, cholesterol and haemoglobin contents This variable composition accounts for variable signal characteristics on MRI, with some components typically demonstrating high T1 signal Calcification is also typically noted involving the solid component (seen with more than 90% of 4 cases ) Page 8 of 33

9 The papillary type has a predominantly solid component and calcification is rare Cystic fluid seen in the papillary type is often not viscous and does 12 not have high T1 signal In both adamantinomatous and papillary type craniopharyngiomas, the solid 9 components often enhance vividly with contrast Germinoma (Fig 8 on page 20) Germinomas are a type of germ cell tumour and are the most common type of tumour of pineal region Up to a fifth of cases occur in the suprasellar region and very rarely the pituitary region They mainly affect the young population (those between 4 the age of 5 to 30 years old) Interestingly, suprasellar germinomas do not have a 3,8 gender prevalence difference whereas pineal germinomas commonly affect males Suprasellar germinomas can manifest either as a primary tumour or as a metastasis from 3 a pineal region germinoma Common clinical presentations include: Endocrine disturbances eg diabetes insipidus or panhypopituitarism Visual defects Hydrocephalus due to compressive effects on the tectal plate Radiographic features Germinomas appear as midline centered tumours They typically appear as well delineated, homogenous and infiltrative masses Cystic degeneration and haemorrhage are rare Because germinomas enhance intensely with contrast on MRI, tumour 8 3 spread can be detected by enhancement in subarachnoid spaces Teratoma (Fig 9 on page 21) Teratomas are rare and account for only 2-4% of brain tumours in the paediatric 16 population They often originate from at least two of three primitive germ cell layers Histologically, they can be categorized into mature, immature or mature with malignant transformation 16 Clinical presentations are location dependent: 1 Intra-axial (present with increased head circumference) Page 9 of 33

10 2 Extra-axial (present with symptoms secondary to mass effect) Radiographic features Due to mixed histology, teratomas often appear as heterogenous lesions with a combination of solid and cystic components The presence of a fat signal is useful in narrowing down the differential diagnosis Calcification is not uncommon Pituitary metastasis (Fig 10 on page 22) Symptomatic pituitary metastases may be found in up to 5% of cancer patients at some 4 point during the course of the disease Breast cancer is the most common source of 9-10 metastasis followed by lung cancer The posterior lobe of the pituitary gland is more commonly affected due to its direct vascular supply from the meningohypophyseal trunk 3 Common clinical presentations include cranial nerve palsies and diabetes insipidus Radiographic features Due to rapid growth, pituitary metastases can appear as a dumbbell shaped mass, often with somewhat ill-defined margins Structure of the sella turcica tends to be often well preserved with no evidence of bony remodeling, but 3,10 bony destruction may be present They may also demonstrate dural thickening Intracranial lipoma (Fig 11 on page 23) Intracranial lipomas represent congenital anomalies and represent less than 1% of 18 intracranial lesions They are typically asymptomatic and are often found incidentally on imaging They result from a maldifferentiation of the embryonic meninx primitiva More than half of intracranial lipomas are associated with other brain malformations such as agenesis or dysgenesis of corpus collosum Common locations include: Pericallosal cistern (45%) Quadrigeminal / superior cerebellar cistern (25%) Page 10 of 33

11 Suprasellar/ interpeduncular cistern (14%) Cerebellopontine angle cistern (9%) Sylvian cistern (5%) Radiographic features Lipomas generally appear as homogenous lesions with typical fat signal characteristics Chemical shift artefacts may also be helpful in the absence of fat saturated 18 images 18 Lymphoma involving the pituitary region (Fig 12 on page 24) Pituitary lymphomas are very rare clinical entities They can be broadly categorized into: 1 2 Primary tumours (more common in males) Secondary tumours 3 The majority of primary CNS lymphomas are represented by non-hodgkin B-cell 19 lymphoma They have similar clinical presentations to other common sellar masses Radiographic features MRI signal characteristics include 3,19 Iso- to hypointense on T1 and T2 weighted sequences The lack of T2 hyperintensity is thought to be due to high cellular density and nucleus to cytoplasmic ratios 19 Shows intense enhancement with contrast 19 Sphenoid sinus metastasis (Fig 13 on page 25) 21 Approximately 1% of paranasal malignancies affect the sphenoid sinus Common primary tumours that can metastasise to paranasal sinuses include (in decreased frequency) kidney, lung and breast 20 Rathke cleft cyst (Fig 14 on page 26) 22 Rathke cleft cysts (RCC's) are rare congenital non-neoplastic cysts Similar to craniopharyngiomas, RCC are derived from the Rathke's pouch A single layer of ciliated Page 11 of 33

12 columnar epithelium typically lines the RCC wall 22 RCC's can occur in any age but 4 are more common in adults They are normally asymptomatic and found incidentally as intrasellar or suprasellar lesions When symptoms develop, they are usually due to compressive effects on the pituitary gland, the optic chiasm or the hypothalamus 23 Radiographic features RCC's may contain serous or mucous fluid, which in turn can give variable 10 imaging appearances They range from being hypo to hyperintense on T1-weighted sequences 70% RCC's are hyperintense while 30% RCC's are iso to hypointense on T2-weighted sequences They normally do not enhance with contrast However, cystic wall 22 8 enhancement may be noted in some cases A small non-enhancing low T2 signal nodule within the cyst is practically a pathognomonic sign of a RCC Calcifications are rarely seen in a RCC 22 Aneurysm of the pituitary region (Fig 15 on page 27) Aneurysms of the pituitary region commonly originate from the cavernous or supraclinoid 3,9 portions of the internal carotid artery In certain cases, aneurysms arising from anterior communicating artery, posterior communicating artery or opthalmic artery may extend 4,10 into the suprasellar cistern Giant aneurysms located in these areas can present with clinical features similar to tumours Differentiating a tumour from an aneurysm is crucial as the two have markedly contrasting management approaches Misdiagnosing a tumour as an aneurysm can have a disastrous surgical outcome, (eg if an aneurysm is perforated during an unwarranted transphenoidal surgery) Thus, when reporting a mass in the pituitary region, it is important to question oneself whether the mass can potentially represent an aneurysm Radiographic features Imaging characteristics vary depending on the degree of thrombus present in the aneurysm Aneurysms are well demarcated and display flow void signal on T1 and T2 4 weighted sequences due to rapid blood flow Page 12 of 33

13 Rapid blood flow may cause significant artefacts in the phase encoding axis 3-4 Thrombosed aneurysms commonly show heterogenous signal intensity on 3 both T1 and T2 weighted sequences Lymphocytic hypophysitis (Fig 16 on page 28) Lymphocytic hypophysitis is a rare chronic inflammatory disorder that can affect the pituitary gland It is believed to be of autoimmune origin and is characterised by infiltration of the pituitary gland by lymphocytes and plasma cells Lymphocytic hypophysitis occurs 3,9-10 primarily in females, especially during pregnancy or in the post-partum period The anterior lobe is usually affected Radiologically it can mimic a pituitary adenoma 3 Common clinical presentations include hypopituitarism, visual disturbances, diabetes 9 insipidus and headaches Lymphocytic hypophysitis often has a favourable response to hormone replacement and steroid therapy 3 Radiographic features The anterior lobe is commonly enlarged and may show vivid homogenous enhancement 10 Adjacent dural enhancement may also be present The posterior lobe bright spot may or may not be preserved 3,10 The pituitary stalk is usually thickened and enlarged 3,10 3,9-10 Page 13 of 33

14 Images for this section: Fig 1: Normal pituitary gland: T1-weighted sagittal image (I: infundibulum ; P: anterior lobe ; *: posterior lobe) with its surrounding structures The posterior lobe is normally T1 hyperintense Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 14 of 33

15 Fig 2: Normal pituitary gland: T1- weighted with contrast coronal image The pituitary gland (red) has a very close relationship with the optic chiasm (green), cavernous sinuses (yellow) and internal carotid arteries (orange) Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 15 of 33

16 Fig 3: Large pituitary microadenoma: appears as a rounded comparatively hypointense lesion within the right side of the pituitary gland with the infundibulum deviated to the left A Dynamic contrast enhanced T1-weighted coronal, B T1-weighted coronal, C T1weighted with contrast coronal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 16 of 33

17 Fig 4: Pituitary macroadenoma: appears as a large mass extending into the suprasellar cistern and compressing the optic chiasm Note the invasion into the left cavernous sinus with encasement of the ICA A T1-weighted sagittal, B T1-weighted with contrast sagittal, C T2-weighted coronal, D T1-weighted with contrast coronal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 17 of 33

18 Fig 5: Suprasellar meningioma: appears as a mass which enhances homogeneously with contrast A dural tail can be seen at the margin of the mass The normal pituitary gland is also noted separate from the lesion A T1-weighted with contrast coronal, B T2weighted coronal, C T1-weighted with contrast sagittal, D T1-weighted sagittal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 18 of 33

19 Fig 6: Adamantinomatous type craniopharyngioma: appears as a multicystic mass with peripheral contrast enhancement Its cystic fluid demonstrates intermediate T1 signal and does not attenuate on FLAIR A T1-weighted axial, B T1-weighted with contrast fat saturation sagittal, C T2-weighted axial, D FLAIR axial Case courtesy of Dr Hani Salam, Radiopaediaorg Page 19 of 33

20 Fig 7: Papillary type craniopharyngioma: appears as a mass with a mixture of predominant solid enhancing and cystic components The cystic fluid is T1 hypointense due to its water like consistency which is more commonly seen in papillary type craniopharyngiomas A T1-weighted axial, B T2-weighted axial, C T1-weighted with contrast coronal, D T1-weighted with contrast sagittal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 20 of 33

21 Fig 8: Germinoma: appears as a mass extending along the floor of the third ventricle and down into the pituitary fossa It enhances homogeneously with contrast The pineal gland is also bulky and demonstrates similiar signal characteritistics The optic chiasm is being compressed by the mass A T1-weighted sagittal, B T2-weighted sagittal, C T1weighted with contrast coronal, D T1-weighted with contrast sagittal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 21 of 33

22 Fig 9: Suprasellar teratoma: appears as suprasellar mass with a predominantly solid component which is T1 hypointense and T2 hyperintense It enhances intensely with contrast Macroscopic fat is also noted at the right inferior margin of the mass (which is a further feature suggestive of a teratoma) A T1-weighted coronal, B T2-weighted coronal, C T1-weighted with contrast coronal, D FLAIR axial Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 22 of 33

23 Fig 10: Pituitary metastasis: appears a "dumbbell" shaped mass with probable anterior dural thickening It extends up along the infundibulum and into the left cavernous sinus There is no evidence of pituitary fossa remodelling A T1-weighted coronal, B T2weighted axial, C T1-weighted with contrast sagittal, D T1-weighted with contrast coronal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 23 of 33

24 Fig 11: Suprasellar lipoma: appears as a suprasellar mass which is T1 and T2 hyperintense (typical fat signal) It becomes saturated out on the fat saturation sequence A T1-weighted axial, B T2-weighted coronal demonstrating promient chemical shift artefact (dark border above, bright border below), C T1-weighted sagittal, D T1-weighted fat saturated sagittal with contrast Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 24 of 33

25 Fig 12: Lymphoma involving the pituitary region: appears as an enlarged and intensely enhancing mass with thickening of the superior infundibulum A T1-weighted sagittal, B T2-weighted coronal, C T1-weighted sagittal with contrast, D T1-weighted coronal with contrast Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 25 of 33

26 Fig 13: Pituitary fossa - sphenoid sinus metastasis: appears as an enhancing mass in the pituitary fossa which extends into the sphenoid sinus The posterior pituitary lobe is elevated and displaced anteriorly A T1-weighted sagittal, B T2-weighted axial, C T1weighted with contrast fat saturated coronal, D T1-weighted with contrast fat saturated axial Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 26 of 33

27 Fig 14: Rathke cleft cyst: appears as a non-enhancing cystic lesion which occupies the anterior part of pituitary fossa, displaces the normal pituitary tissue posteriorly It is T1 hypointense and T2 hyperintense The cyst almost touches the optic chiasm A small T2 hypointense nodule is noted at the anteroinferior aspect of the cyst, which is virtually a pathognomonic sign of a RCC A T1-weighted sagittal, B T2-weighted coronal, C T1weighted with contrast sagittal, D T2-weighted coronal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 27 of 33

28 Fig 15: Internal carotid aneurysm: Coronal CT angiogram maximum intensity projection reconstruction demonstrates a large left ICA aneurysm within an enlarged pituitary fossa The floor of the fossa is deficient and the aneurysm bulges into the sphenoid sinus T1 and T1 C+ sagittal demonstrate rounded mass with heterogeneous signal due to flow T2 coronal demonstrates mainly flow void A T1-weighted sagittal, B T1-weighted with contrast sagittal, C T2-weighted coronal, D CT angiogram coronal Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 28 of 33

29 Fig 16: Lymphocytic hypophysitis: appears as an enhancing soft tissue mass involving the anterior and posterior pituitary as well as the infundibulum (which is markedly expanded) The superior component severely compresses and elevates the optic chiasm A T1-weighted sagittal, B T1-weighted sagittal with contrast, C T1-weighted axial with contrast, D T1-weighted fat saturated coronal with contrast Case courtesy of Dr Frank Gaillard, Radiopaediaorg Page 29 of 33

30 Conclusion When interpreting a mass in the pituitary region, it is important for the radiologist to be familiar with the pathological spectrum of lesions that can occur in this region A greater knowledge of subtle differences in MRI features of these conditions will enable radiologists to give a better and more concise differential diagnosis, and in some cases avoid adverse patient outcomes with unnecessary surgery We hope that this pictorial essay was useful in improving your understanding of lesions in the pituitary region Page 30 of 33

31 Personal information Dr Chia Wei Oh, Lawrence MBBS PGDipSurgAnat Resident Medical Officer Monash Medical Centre Dr Frank Gaillard MBBS PGDipSurgAnat MMed FRANZCR Consultant Neuroradiologist Royal Melbourne Hospital Dr Yuranga Weerakkody MBChB FRANZCR Consultant Radiologist Royal Perth Hospital Page 31 of 33

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