EXPERT DIFFERENTIAL DIAGNOSIS:

Sellar Region

Anne G. Osborn, M.D.

DISCLOSURE:Published RSNA 2008

SELLA, PITUITARY:Normal Gross, 3T Anatomy

SELLA, PITUITARY:Anatomically-Based Differential Diagnoses

• Intrasellar• Sella/pituitary, normal variants

• Enlarged pituitary gland

• Intrasellar lesion

• Cystic intrasellar mass

• Suprasellar• Suprasellar mass, general

• Suprasellar mass, pediatric

• Suprasellar cystic mass

• Calcified suprasellar mass

• Thick infundibular stalk

SELLA/PITUITARY:Normal Variants

• Common• Pituitary hyperplasia (physiologic)

• Pituitary “incidentaloma”

• “Empty” sella

• Less common• “Bright” pituitary gland

• Absent posterior pituitary “bright spot”

• Small sella turcica

• “J”-shaped sella

• Rare but important• Paramedian (“kissing”) internal carotid arteries

PITUITARY HYPERPLASIA (PHYSIOLOGIC)

• Must know age, gender!!• Physiologic ↑

• 10-15 mm• Convex upwards• Strong, uniform enhancement

• Can be indistinguishable from• Macroadenoma• Lymphocytic hypophitis• Metastasis, lymphoma

• Beware: “Macroadenoma” in prepubescent males!

Postpartum lactating

21y menstruating ♀

14 mm

11 mm

PITUITARY “INCIDENTALOMA”

• Inhomogeneous or nonenhancing “filling defect”• 15-20% normal MRs

• Can also be transient

• Etiology• Nonneoplastic cyst (e.g., pars

intermedia, Rathke cleft)

• Nonfunctioning microadenoma (common at autopsy)

“EMPTY” SELLAPrimary (i.e., not post-surgical)

Courtesy M.

Sage

MISCELLANEOUS NORMAL VARIANTS

“Bright” pituitary “Shallow” sella

Small sella “Kissing” carotids

ENLARGED PITUITARY

• Common• Pituitary hyperplasia

• Microadenoma

• Macroadenoma

• Less common• Neurosarcoid

• LCH

• Lymphocytic hypophysitis

• Macroadenoma mimics

• Rare but important• Intracranial hypotension

• Meningioma

• Metastasis

• dAVF

• Pituicytoma

• Pseudotumor

• Lymphoma

• Leukemia

ENLARGED PITUITARY

Neurosarcoid LCH

Lymphoma Pseudotumor

ENLARGED PITUITARY

Macro mimic

(“shallow sella”)Intracranial

hypotension

Lymphocytic

hypophysitisMetastasis

INTRASELLAR LESION

• Common• Pituitary hyperplasia• Microadenoma• “Empty” sella

• Less common• Macroadenoma• Rathke cleft cyst• Craniopharyngioma• Neurosarcoid

• Rare but important• Lymphocytic hypophysitis• Intracranial hypotension• “Kissing” carotids• Aneurysm• Meningioma• Metastasis• Lymphoma• dAVF• CNS siderosis (“black”

pituitary)

• Hepatic encephalopathy (“white pituitary”)

MICROADENOMA

•Variable histology

• Prolactinoma 30%

• GH 20%

• Null cell 20%

• ACTH 10%

• FSH/LH 10%

• PRL-GH 5%

• Mixed, TSH 1-5%

• Incidental pituitary lesions are common

• 17% in autopsy series

MICROADENOMA

• Pituitary Microadenoma• 10mm or less

• 10-20% of autopsies

• Micro >>> Macro

• Dynamic Imaging

• Increases sensitivity (10-30% seen only on dynamic MR)

• Enhances slower than normal gland

MICROADENOMA

RATHKE CLEFT CYST

• Intrasellar 40%

• Suprasellar extent 60%

• 3mm – 3cm

• Most incidental

• Symptomatic• Pituitary dysfunction

• Visual change, HA

• Look for• Intracystic nodule

• “Claw sign”

MISCELLANEOUS INTRASELLAR LESIONS

• Craniopharyngioma• Completely intrasellar is rare

• Variable signal

• CNS siderosis• “Black” pituitary on T2*

• Iron overload states >> SAH

• Thalassemia

• Hemochromatosis

Craniopharyngioma

Siderosis

CYSTIC-APPEARING INTRASELLAR MASS

• Common• Empty sella

• Intracranial hypertension, idiopathic

• Less common• Obstructive

hydrocephalus

• Rathke cleft cyst

• Craniopharyngioma

• Arachnoid cyst

• Epidermoid cyst

• Neurocysticercosis

• Rare but important• Pituitary apoplexy

• Saccular aneurysm (thrombosed)

CYSTIC INTRASELLAR MASS

• Key question• Cystic mass originating WITHIN sella?

• Intrasellar extension from suprasellar cystic lesion

• Intrasellar extension of suprasellar lesion >> cystic intrasellar mass

INTRACRANIAL HYPERTENSION (IDIOPATHIC)

• A.k.a. “pseudotumor cerebri”• ↑ ICP without underlying

pathology• Young obese female• Imaging

• Partial empty sella• Dilation/tortuosity of optic n. sheath• Posterior globe flattened• ↓ Subarachnoid spaces, sulci

• Small (“slit-like”) ventricles seen in only 10%

INTRASELLAR CYSTIC LESIONS

Hydrocephalus Craniopharyngioma

Epidermoid cystRathke cleft cyst

INTRASELLAR CYSTIC LESIONS

Arachnoid cyst Neurocysticercosis

Pituitary apoplexy

(Sheehan)

Thrombosed

aneurysm

SUPRASELLAR MASS, GENERAL

• Common• Macroadenoma• Meningioma• Saccular aneurysm• Craniopharyngioma• Pilocytic astrocytoma

• Less common• Dilated 3rd ventricle• Arachnoid cyst• Neurocysticercosis• Rathke cleft cyst• Neurosarcoid• LCH• Germinoma• Dermoid cyst• Lipoma

• Rare but important• Lymphocytic hypophysitis• Pituitary apoplexy• Tuber cinereum hamartoma• Epidermoid cyst• Pituicytoma• Diffuse astrocytoma• Pilomyxoid astrocytoma• Ectopic neurohypophysis• Metastasis• Lymphoma• Leukemia• Cavernous malformation• Tuberculoma• Pituitary abscess

SUPRASELLAR MASS, GENERAL

• “Big 5” = 75%

• The “big kahuna”• Macroadenoma (35%-50%)

• Approximately 10%• Meningioma

• Aneurysm

• Craniopharyngioma

• Astrocytoma (hypothalamic-chiasmatic)

SUPRASELLAR MASS, GENERAL:Key Questions to Consider

• Is the patient adult or child? • Is the mass intra- or extra-axial?• If extra-axial, does it arise from pituitary?

• Can you identify pituitary gland separate from mass?• Or is the gland the mass?• Does it mostly involve the infundibular stalk?

• Intra-axial masses arise from• Optic chiasm, hypothalamus• 3rd ventricle

• Is the mass cystic or solid?• If cystic, is it exactly like CSF?

SUPRASELLAR MASS, PEDIATRIC

• Common• Pilocytic astrocytoma• Craniopharyngioma• Pituitary hyperplasia• Hydrocephalus (↑ 3rd v.)

• Less common• Germinoma• Tuber cinereum

hamartoma• Arachnoid cyst• LCH• Stalk anomalies• Teratoma

• Rare but important• Lipoma• Macroadenoma• Dermoid cyst• Pilomyxoid aneurysm• Saccular aneurysm• Trilateral retinoblastoma• Lymphocytic hypophysitis• Lymphoma/leukemia• Rathke cleft cyst

PILOCYTIC ASTROCYTOMA

CRANIOPHARYNGIOMA

• 2nd most common suprasellar mass in children

• Peak incidence 5-15 yrs• Second peak 50-60 yrs

• M = F• Visual changes• Endocrine dysfunction• Mass effect

• H/A, N, V, papilledema• Imaging

• 90% Ca++, 90% cystic• 90% enhance• Cysts variable intensity

GERMINOMA

• Suprasellar region is second most common site

• M = F suprasellar

• 90% present < 20 yrs

• Endocrine dysfunction

• Diabetes insipidus

• Panhypopituitarism

• Radiosensitive

• Up to 90% 10 survival

GERMINOMA

• Imaging

• Combined lesion typical but may affect only infundibular stalk

• May be hyperdense (CT)

• Isointense T1WI

• Hyper- to isointense T2WI

• Enhances homogeneously

• CSF dissemination common

TUBER CINEREUM HAMARTOMA

•Clinical• Precocious puberty

• Usually < 2yrs

• Gelastic seizures

• M > F

• Pallister-Hall

• Facial anomalies

• Polydactyly

• Imperforate anus

•Pathology• Congenital nonneoplastic

heterotopia

• Between infundibular stalk, mamillary bodies

TUBER CINEREUM HAMARTOMA

SUPRASELLAR CYSTIC MASS

• Common• Hydrocephalus (↑ 3rd v)

• Arachnoid cyst

• Craniopharyngioma

• Neurocysticercosis

• Less common• Rathke cleft cyst

• Dermoid cyst

• Epidermoid cyst

• Enlarged PVSs

• Rare but important• Macroadenoma

• Pituitary apoplexy

• Astrocytoma (pilocytic, pilomyxoid)

• Ependymal cyst

• Saccular aneurysm (partially/completely thrombosed)

HYDROCEPHALUS vs. ARACHNOID CYST

• Hydrocephalus• 3rd v easily identified, dilated

• May project into sella

• Signal CSF-like

• Arachnoid cyst• 10% suprasellar

• 3rd v elevated/compressed, often difficult to identify

• CSF may be slightly different signal from cyst

Hydrocephalus

Arachnoid cyst

RATHKE CLEFT CYST

• 60% suprasellar

• Variable size• Can be tiny (intra-

pituitary)

• Can be huge!!

• May widen, erode sella

• Variable signal

• Look for• Intracystic nodule

• “Claw sign”

MISCELLANEOUS SUPRASELLAR CYSTS, CYSTIC-APPEARING

MASSES

Craniopharyngioma Neurocysticercosis

Astrocytoma Pituitary apoplexy

CALCIFIED SUPRASELLAR MASS

• Common• Atherosclerosis

• Craniopharyngioma

• Meningioma

• Aneurysm (saccular, fusiform)

• Less common• Neurocysticercosis

• Pilocytic astrocytoma

• Dermoid cyst

• Rare but important• Macroadenoma

• Tuberculosis

• Chondroid tumor

CALCIFIED SUPRASELLAR MASS

• Key questions• Is Ca++ curvilinear, punctate, globular?

• Does lesion enhance?

CALCIFIED SUPRASELLAR MASS:Atherosclerosis

• Atherosclerosis• Older patient

• Curvilinear Ca++

• Bilateral, multi-focal

• Aneurysm• Saccular (ring, arc)

• Fusiform (curvilinear) Ca++

CALCIFIED SUPRASELLAR MASS:Miscellaneous

Craniopharyngioma Meningioma

Dermoid cyst Macroadenoma

THICK INFUNDIBULAR STALK:Key Issues

• Know what normal stalk looks like!• Tapers from top to bottom

• 2 mm or less diameter

• Thick stalk• > 2mm

• Nontapering

• Patient age extremelyimportant• Child = LCH, germinoma

• Adult = sarcoid, hypophysitis, pituicytoma, metastasis, lymphoma

THICK STALK

Child Adult

Germinoma

Histiocytosis

Sarcoid

Lymphoma

SUMMARY

• Know patient age, clinical/lab

• Determine lesion “sublocation”• Intrasellar

• Suprasellar

• Infundibular stalk

• Remember the “Big Five”

• Find pituitary separate from mass?• No (if gland is mass, consider macroadenoma,

metastasis, hypophysitis, lymphoma)

• Yes (consider meningioma, aneurysm, cyst, etc.)