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 Differential Diagnosis of Nervous System Disorders

Destruction of Sella  !!navigator!!

  1. Pituitary adenoma
  2. Suprasellar tumor
  3. Carcinoma of sphenoid + posterior ethmoid sinus
    • opacification of sinus + destruction of walls
    • associated with nasopharyngeal mass (common)
  4. Nasopharyngeal carcinoma
    1. squamous cell carcinoma
    2. lymphoepithelioma = Schmincke tumor = nonkeratinizing form of squamous cell carcinoma
    • sclerosis of adjacent bone
  5. Metastasis to sphenoid: from breast, kidney, thyroid, colon, prostate, lung, esophagus
  6. Primary tumor of sphenoid bone (rare): osteogenic sarcoma, giant cell tumor, plasmacytoma
  7. Chordoma
  8. Mucocele of sphenoid sinus (uncommon)
  9. Enlarged 3rd ventricle aqueductal stenosis ← infratentorial mass, maldevelopment

J-shaped Sella  !!navigator!!

mnemonic: “CONMAN”

  • Chronic hydrocephalus
  • Optic glioma, Osteogenesis imperfecta
  • Neurofibromatosis
  • Mucopolysaccharidosis
  • Achondroplasia
  • Normal variant

Enlarged Sella  !!navigator!!

  1. PRIMARY TUMOR
    1. Pituitary adenoma
    2. Craniopharyngioma
    3. Meningioma: hyperostosis
    4. Optic glioma: J-shaped sella
  2. PITUITARY HYPERPLASIA
    1. Hypothyroidism
    2. Hypogonadism
    3. Nelson syndrome
      • = rapid enlargement of pre-existing ACTH-secreting pituitary adenoma
      • Frequency: in 7% of patients after removal of both adrenal glands
      • Cause: absence of negative feedback of cortisol on production of ACTH
  3. CSF SPACE
    1. Enlarged 3rd ventricle
    2. Hydrocephalus
    3. Empty sella
  4. VESSEL
    1. Arterial aneurysm
    2. Ectatic internal carotid artery

mnemonic: CHAMPS

  • Craniopharyngioma
  • Hydrocephalus (empty sella)
  • AVM, Aneurysm
  • Meningioma
  • Pituitary adenoma
  • Sarcoidosis, TB

Pituitary Gland Enlargement

  1. Neoplasm: eg, pituitary gland adenoma
  2. Hypertrophy: primary precocious puberty, primary hypothyroidism
  3. Lymphocytic hypophysitis
  4. Infection
  5. Severe dural AV fistula

Complex Sellar / Parasellar Cyst  !!navigator!!

  1. Cystic craniopharyngioma
  2. Hemorrhagic pituitary adenoma
  3. Hemorrhagic / proteinaceous Rathke cleft cyst

Intrasellar Mass  !!navigator!!

  1. Pituitary adenoma / carcinoma (most common cause)
  2. Craniopharyngioma (2nd most common cause)
  3. Meningioma: from surface of diaphragm / tuberculum sellae
  4. Chordoma
  5. Metastasis: lung, breast, prostate, kidney, GI tract, spread from nasopharynx
  6. Intracavernous ICA aneurysm: bilateral in 25%
  7. Pituitary abscess: rapidly expanding mass associated with meningitis
  8. Empty sella
  9. Rathke cleft cyst: commonly at junction of anterior + posterior pituitary gland
  10. Choristoma: benign neoplasm of posterior pituitary gland
  11. Granuloma: sarcoidosis, giant cell granuloma, TB, syphilis, eosinophilic granuloma
  12. Lymphoid adenohypophysitis
  13. Pituitary hyperplasia, eg, in Nelson syndrome

Calcified Sellar Lesion

  1. Aneurysm
  2. Craniopharyngioma
  3. Chordoma
  4. Cartilaginous tumor

Decreased T2 Signal Intensity of Pituitary Gland

  1. Hemochromatosis
  2. Malignant melanoma
  3. Pituitary hemorrhage
  4. Flow void (aneurysm)
  5. Rathke cleft cyst
  6. Calcification (craniopharyngioma, chordoma)

Hypointense Lesion of Sella  !!navigator!!

  1. Empty sella
  2. Pituitary stone (= pituilith)
    = sequelae of autonecrosis of pituitary adenoma
  3. Intrasellar aneurysm
  4. Persistent trigeminal artery
  5. Calcified meningioma
  6. Pituitary hemochromatosis (anterior pituitary lobe only)

Thickened Pituitary Stalk  !!navigator!!

  1. Langerhans cell histiocytosis
  2. Germinoma
  3. Craniopharyngioma
  4. Tuberculosis
  5. Sarcoidosis
  6. Lymphocytic hypophysitis

Parasellar Mass  !!navigator!!

  1. Meningioma: tentorium cerebelli
  2. Neurinoma (III, IV, V1, V2, VI)
  3. Metastasis: lung, breast, kidney, GI tract, spread from nasopharynx
  4. Epidermoid
  5. Aneurysm
  6. Carotid-cavernous fistula

Suprasellar Mass  !!navigator!!

  1. Meningioma
  2. Craniopharyngioma: in 80% suprasellar
  3. Chiasmal + optic nerve glioma in 38% of neurofibromatosis; adolescent girls
    DDx: chiasmal neuritis
  4. Hypothalamic glioma
  5. Hamartoma of tuber cinereum
  6. Infundibular tumor: metastasis (esp. breast); glioma; lymphoma / leukemia; histiocytosis X; sarcoidosis; tuberculosis
    • diameter of infundibulum >4.5 mm immediately above level of dorsum; cone-shaped (on coronal scan)
  7. Germinoma
    = malignant tumor similar to seminoma (= “ectopic pinealoma”)
    • frequently calcified (teratoma)
    • CSF spread (germinoma + teratocarcinoma)
    • enhancement on CECT (common)
  8. Epidermoid / dermoid
    • cystic lesion containing calcifications + fat
    • minimal / no contrast enhancement
  9. Arachnoid cyst
    • hydrocephalus (common), visual impairment
    • endocrine dysfunction

    Age: most common in infancy
  10. Enlarged 3rd ventricle extending into pituitary fossa
  11. Suprasellar aneurysm
    • rim calcification + eccentric position

Suprasellar Mass in Adulthood

mnemonic: SATCHMO

  • Sarcoidosis, Sella neoplasm with superior extension
  • Aneurysm (ectatic carotid, carotid-cavernous sinus fistula), Arachnoid cyst, Adenoma (pituitary)
  • Tuberculosis, Teratoma: dysgerminoma (usually), dermoid, epidermoid
  • Craniopharyngioma, Chordoma
  • Hypothalamic glioma, Histiocytoma, Hamartoma
  • Meningioma, Metastatic disease, Mucocele
  • Optic nerve glioma, neuroma

Suprasellar Mass with Low Attenuation

  1. Craniopharyngioma
  2. Dermoid / epidermoid
  3. Arachnoid cyst
  4. Lipoma
  5. Simple pituitary cyst
  6. Glioma of hypothalamus

Suprasellar Low-density Lesion with Hydrocephalus

  1. CYST
    1. Arachnoid cyst
    2. Ependymal cyst of 3rd ventricle
    3. Parasitic cyst of 3rd ventricle (cysticercosis)
    4. Dilated 3rd ventricle (in aqueductal stenosis)
  2. CYSTIC MASS
    1. Epidermoid
    2. Hypothalamic pilocytic astrocytoma
    3. Cystic craniopharyngioma

N.B.: Cystic lesion may be inapparent within surrounding CSF; metrizamide cisternography is helpful in detection + to exclude aqueduct stenosis

Suprasellar Mass with Mixed Attenuation

  1. IN CHILDREN
    1. Hypothalamic-chiasmatic glioma
    2. Craniopharyngioma
    3. Hamartoma of tuber cinereum
    4. Histiocytosis
  2. IN ADULTS
    1. Suprasellar extension of pituitary adenoma
    2. Craniopharyngioma
    3. Epidermoid cyst
    4. Thrombosed aneurysm
    5. Low-grade hypothalamic / optic glioma
    6. Inflammatory lesion: sarcoidosis, TB, sphenoid mucocele

Suprasellar Mass with Calcification

  1. CURVILINEAR
    1. Giant carotid aneurysm
    2. Craniopharyngioma
  2. GRANULAR
    1. Craniopharyngioma
    2. Meningioma
    3. Granuloma
    4. Dermoid cyst / teratoma
    5. Optic / hypothalamic glioma (rare)

Hyperintense Suprasellar Mass on T1WI

  1. Craniopharyngioma
    • viscous material in cystic region (protein concentration of 10-30%)
    • intrasellar component in 70%
  2. Germinoma
    • hemorrhagic mass → methemoglobin
    • most common in adolescent girls
    • diabetes insipidus
  3. Thrombosed aneurysm
    • laminated internal architecture ← thrombus of differing age (best appreciated on T2WI)
  4. Rathke cleft cyst
    • containing thickly mucinous material
    • no contrast enhancement
    • intra- / suprasellar in location
  5. Dermoid cyst
    • with predominantly sebaceous material
    • suppressed by fat saturation scan
  6. Lipoma at floor of 3rd ventricle
    • round + homogeneous
    • suppressed by fat saturation scan
  7. Ectopic neurohypophysis
    • along floor of 3rd ventricle
    • quite small
  8. Cavernous angioma
    = collection of sinusoidal spaces
    • occasionally familial
    • multinodular “popcorn” aggregate with central zones of T1 shortening surrounded by rind of T2 shortening
    • frequently multiple
    • angiographically occult /cryptic
  9. Hemorrhagic metastasis

Suprasellar Mass with Uniform Enhancement

  1. Pituitary adenoma
  2. Pituitary Hyperplasia
    • symmetrical masslike contour
    • appropriate clinical setting (hypothyroidism, pregnancy)
  3. Meningioma
    • midline suprasellar lesion
  4. Lymphocytic adenohypophysitis
    • usually in women during postpartum period
    • diabetes insipidus common
    • suprasellar extension common
  5. Chiasmatic / hypothalamic glioma
  6. Unusual craniopharyngioma
  7. Langerhans histiocytosis
  8. Germinoma

Enhancing Supra- and Intrasellar Mass  !!navigator!!

  1. Pituitary adenoma
  2. Meningioma
  3. Germinoma
  4. Hypothalamic glioma
  5. Craniopharyngioma

Perisellar Vascular Lesion  !!navigator!!

  1. ICA aneurysm
    • Giant aneurysms are those >2.5 cm in diameter
    • destruction of bony sella / superior orbital fissure
    • calcified wall / thrombus
    • CECT enhancement, nonuniform with thrombosis
  2. Ectatic carotid artery
    • curvilinear calcifications
    • encroachment upon sella turcica
  3. Carotid-cavernous sinus fistula

Lesion Expanding Cavernous Sinus  !!navigator!!

  1. TUMOR
    1. Trigeminal schwannoma
    2. Pituitary adenoma
    3. Parasellar meningioma
    4. Parasellar metastasis
    5. Invasion by tumor of skull base
  2. VESSEL
    1. Internal carotid artery aneurysm
    2. Carotid-cavernous fistula
    3. Cavernous sinus thrombosis
  3. Tolosa-Hunt syndrome (← cavernous sinus inflammation)

 Outline