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…
KEY FACTS Imaging Best clue Anterior or central skull base ( SB ) defect on bone CT with positive β2-transferrin test on nasal secretions Anterior SB bone CT findings Bone defect in cribriform plate, lateral lamella of middle turbinate or…
KEY FACTS Terminology Headache caused by ↓ intracranial CSF pressure Imaging Classic imaging Diffuse dural thickening/enhancement – Smooth, not nodular or “lumpy-bumpy” Downward displacement of brain through incisura (“slumping” midbrain) Veins, dural sinuses distended ± subdural hygromas/hematomas Other: Midbrain elongated,…
Overview Understanding the anatomy of the skull, scalp, and meninges is key to formulating a correct imaging diagnosis. Several important differential diagnoses are based on location. However, each of these locations requires a different imaging approach. For example, CT is…
KEY FACTS Terminology Definition: Cerebellopontine angle-internal auditory canal (CPA-IAC) metastases refers to systemic or CNS neoplasia affecting area of CPA-IAC Imaging 4 major sites: Leptomeningeal (pia-arachnoid), dura, flocculus, and choroid plexus T1WI C+ MR Leptomeningeal metastases : Diffuse thickening and…