KEY FACTS Terminology Typical (benign) meningioma = WHO grade I Atypical meningioma (AM) = WHO grade II Malignant meningioma (MM) = WHO grade III Imaging CT triad of MM: Extracranial mass, osteolysis, intracranial tumor MR Dural-based locally invasive lesion with…
KEY FACTS Imaging Intradural extramedullary mass Thoracic (80%) > cervical (16%) > lumbar (4%) Typically round or ovoid (en globe) En plaque variety pancaked or flat along dura Broad-based dural attachment Strong homogeneous enhancement Prominent “dural tail” less common than…
KEY FACTS Terminology Trichilemmal cyst (TC) is preferred term Sebaceous cyst commonly used but incorrect Variant = proliferating trichilemmal tumor Keratin-containing cyst Lined by stratified squamous epithelium Pathology looks like root sheath of hair follicle Imaging General features Most within…
KEY FACTS Terminology Multisystem inflammatory disease characterized by noncaseating epithelioid-cell granulomas Imaging Solitary or multifocal CNS mass(es) ± abnormal CXR CXR abnormal in > 90% with neurosarcoid (NS) Wide spectrum of MR manifestations Dura-arachnoid thickening (diffuse or focal)) May coat…
KEY FACTS Terminology Langerhans cell histiocytosis (LCH) LCH now best understood as neoplastic disease Activating somatic BRAF mutations, LCH cell clonality Imaging NECT Sharply marginated lytic skull defect – Beveled edges Mastoid: Geographic destruction, soft tissue mass MR Absent posterior…
KEY FACTS Terminology Skull thickening (ST) Diploic space expanded ± thickened cortex Imaging Widened calvaria (skull width) Can be diffuse or focal NECT best for most causes of ST Thin-section bone CT for detailed skull base evaluation MR C+ contrast:…
KEY FACTS Terminology Chronic metabolic skeletal disorder Characterized by bony expansion with variable destruction ± sclerosis Imaging Well-circumscribed, sharply marginated defects &/or marked thickening + sclerosis Skull in 25-65% (may be isolated to skull base) Diploic widening, coarse trabecula, thick…
KEY FACTS Terminology Fibrous dysplasia (FD) Synonyms: Craniofacial fibrous dysplasia (CFD), osteitis fibrosa, osteodystrophy fibrosa McCune-Albright syndrome (MAS) 1 of most common FD syndromes Congenital disorder characterized by expanding lesion(s) Defect in osteoblastic differentiation, maturation Contains mixture of fibrous tissue,…
KEY FACTS Terminology IgG4-related disease (IgG4-RD) Chronic fibroinflammatory disease characterized by IgG4(+) plasma cell infiltrates Imaging Diffusely infiltrating enhancing mass Orbital adnexa (lacrimal gland most common) Dura-arachnoid (IgG4-related hypertrophic pachymeningitis) Pituitary gland, stalk (hypophysitis) Other: Cranial nerves (especially infraorbital nerve),…
KEY FACTS Terminology Definition: Nonspecific, nonneoplastic benign inflammatory lesion without identifiable local or systemic causes characterized by polymorphous lymphoplasmacytic infiltrate Idiopathic orbital inflammation May involve any part(s) of orbit Idiopathic extraorbital inflammation Intracranial involvement : Spread through superior orbital fissure…