Face & Neck

Question 1

What is the DDx for rectus muscle thickening?

Answer 1

Inflammatory:

1: Thyroid opthalmopathy (Grave’s disease): starts with medial and inferior recti muscles.
2: Orbital myositis: rapid onset of proptosis, erythema of the lids. Rx.: steroids.
3: Orbital pseudotumour

Neoplasms:

4: Rhabdomyosarcoma: rare, boys <10, enhancing mass often with adjacent bony destruction. Optic nerve displaced but not involved.
5: Metastasis: lymphoma, leukaemia

Vascular:
6: Carotid-cavernous fistula: usually presents with proptosis and enlargement of the superior opthalmic vein.

Question 2

DDx for orbital masses arising from the globe?

Answer 2

1: Retinoblastoma: Children; Ca +++; on CT soft tissue component shows minimal or no enhancement unlike in persistent hyperplastic primary vitreous (PHPV). MRI: slightly high T1 with enhancement and slightly low T2
2: Melanoma: Mass arises from choroid. Demonstrates enhancement. High on T1 due to melanin.
3: Detachment and choroidal effusion

Question 3

DDx for thickening of the optic nerve

Answer 3

1: Optic nerve glioma
2: Optic nerve meningioma
3: Optic neuritis

Question 4

DDx for “Bare” orbit?

Answer 4

1: Neurofibromatosis:- from dysplasia of the sphenoid
2: Metastasis:- bone destruction
3: Meningioma: due to hyperostosis