Face and neck
11.1
Orbital mass lesions
Lesions involving the globe
1. Retinoblastoma – usually presents with white pupil; 20–40% bilateral, 10% have family history; four main subgroups:
(c) Chromosomal – associated with partial deletion of chromosome 13.
(d) ‘Trilateral’ retinoblastoma – bilateral retinoblastoma with pineal tumour.
90% show (various patterns of) calcification.
2. Melanoma – increased incidence from middle age; avidly enhances; may be high signal on precontrast T1 if melanotic.
Intraconal lesions
Conal lesions
2. Thyroid eye disease – enlargement of muscles; swelling of intraorbital fat.
3. Rhabdomyosarcoma – 10% arise in orbit, 50% < 7 years of age; rapid-onset proptosis with deviation of globe; although arises in muscle most of tumour usually extraconal; differentiation between orbital and extraorbital (parameningeal) origin important as treatment differs.
Extraconal lesions
1. Orbital cellulitis and abscess – coronal sections with contrast most sensitive, especially for small subperiosteal collections; secondary to paranasal sinus infection.
4. Dermoid – commonest at external angle.
5. Lymphangioma/lymphaemangioma.
6. Direct extension of lacrimal gland tumour.
7. Langerhans’ cell histiocytosis.
11.2
Optic nerve glioma versus optic nerve sheath meningioma – clinical and radiological differentiation
| Glioma | Meningioma |
| 50% < 5 years of age | Usually middle-aged women |
| ± Bilateral | Usually unilateral |
| Slowly progressive, painless loss of vision; central scotoma Childhood tumours may remain quiescent for years, particularly in the presence of NF Adult tumours more aggressive |
Slowly progressive, painless loss of vision; proptosis |
| Neurofibromatosis*: NF-1 in 25%; 15% of NF-1 have optic nerve glioma; bilateral disease strongly suggests neurofibromatosis | Neurofibromatosis (1 or 2) in 4–6%; bilateral disease may occur with or without NF |
| No orbital hyperostosis | Hyperostosis |
| Widened optic canal in 90% but intracranial extension is unusual | Widened optical canal in 10% |
| Kinking and buckling of the optic nerve is common. Smooth outline | Straight optic nerve, but tumour may be eccentric |
| Well-defined margins | More infiltrative Localized or fusiform thickening |
| Calcification rare without prior radiotherapy | Calcification (linear, plaque-like or granular) more common |
| Isointense to brain on T1W MRI; hyperintense on T2W MRI | Similar signal to optic nerve on most unenhanced MR pulse sequences |
| Variable contrast enhancement with mottled lucencies due to mucinous degeneration | Diffuse homogeneous enhancement ± serrated margins |
| Negative image of optic nerve within the tumour (tram-track sign) |
