Unilateral Cavernous Sinus Mass

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Lateral dural walls of cavernous sinuses (CSs) should be flat or concave on axial/coronal imaging
- Convex outer margin indicates abnormality
- Lateral dural wall thick, easy to see; medial = thin, difficult to delineate
CSs are septated (not single pool of venous blood)
CSs enhance strongly but contain normal filling “defects” (Meckel cave, cranial nerves, ICA)
If mass present, is it intrinsic or extrinsic to cavernous sinus?
Where does mass originate?
- Sella: Pituitary macroadenoma
- Sphenoid sinus/central skull base: Metastasis, nasopharyngeal carcinoma
- Dura: Meningioma, hemangioma, pseudotumor
Does it contain “flow voids”?
- Aneurysm
- Dural AVF

Helpful Clues for Common Diagnoses

Pituitary Macroadenoma
- Cavernous sinus invasion common with macroadenoma
- Difficult to determine unless florid
- Mass, gland indistinguishable (gland IS mass)
Meningioma
- Diffusely infiltrates sinus, thickens dura
- Lateral dural wall can sometimes be identified within thickened, intensely enhancing CS mass
- Look for dural “tail” along clivus, tentorium
- Look for other meningiomas (multiple meningioma syndrome)
Schwannoma
- Most common = trigeminal, in Meckel cave
- Typically well-marginated
- Usually hyperintense on T2WI
- Solitary > multiple (NF2)
Metastases, Skull and Meningeal
- Three patterns
  - Hematogenous (direct or extension from skull base)
  - Perineural along cranial nerve (usually from nasopharyngeal or sinus tumor)
  - Direct geographic invasion (squamous cell, minor salivary gland tumors most common primaries)
Lymphoma, Metastatic, Intracranial
- Primary CS rare; usually history of disease elsewhere
Nasopharyngeal Carcinoma
- Two patterns
  - Direct cephalad extension into central skull base, CS
  - Perineural extension into cavernous sinus(es) along CNV2

Helpful Clues for Less Common Diagnoses

Saccular Aneurysm
- Can be spontaneous, post-traumatic (pseudoaneurysm)
- Can be patent or partially thrombosed
- Prominent “flow void”, pulsation (phase) artifact
Carotid-Cavernous Fistula, Traumatic
- Superior ophthalmic vein enlarged
- ± Basilar skull fracture
- Usually at junction of vertical, horizontal ICA segments
Thrombosis, Cavernous Sinus
- Nonenhancing thrombus, thickened enhancing dural walls
- May be secondary to sinusitis (thrombophlebitis)
- Superior ophthalmic vein(s) often enlarged
- Proptosis common
Dermoid Cyst
- Typically in Meckel cave, not CS proper
- Fat density/signal intensity
Epidermoid Cyst
- Typically in Meckel cave, not CS proper
- CSF density/signal intensity
- Usually occurs as extension from CPA lesion
Neurosarcoid
- Can be uni- or bilateral
- Look for thickened infundibular stalk, dural masses
Pseudotumor, Intracranial
- Uni- > bilateral
- Typically extends posteriorly from orbital apex into CS
- Extensive dural enhancement along middle fossa can be present
- Occasionally can be invasive, destructive; mimics neoplasm or aggressive infection
Hemangioma
- True vasoformative neoplasm in CS, dura
- May mimic meningioma

Helpful Clues for Rare Diagnoses

Plexiform Neurofibroma
- Occurs only in NF1
- Involves cutaneous, orbital branches of CN5
- Infiltrative, unencapsulated mass
- Look for
  - Scalp neurofibromas
  - Sphenoid wing dysplasia
Chordoma
- Destructive mass, midline > lateral
- Occasionally can originate in CS or extend asymmetrically from clivus into CS
- Most are very hyperintense on T2WI
Tuberculosis
- History of pulmonary TB
- Dura-arachnoid thickening from basilar meningitis
Iatrogenic
- Post-operative packing after trans-sphenoidal macroadenoma resection
- Look for surgical defect in sellar floor
- Caused by overpacking of defect
- May appear very bizarre
- Fat suppression sequence helpful