[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › [Eye](https://durgical.com/en/general-pathology/areas/eye/) › Orbital disease

# Orbital disease

- Lesion

Anything that fills the orbit pushes the eye forward: swollen muscles in Graves disease, inflammation, infection or a tumour.

Updated Nov 12, 2026

## Key points

- Thyroid-associated orbitopathy: TSH-receptor antibodies activate orbital fibroblasts; glycosaminoglycans and lymphocytes swell the muscles, sparing the tendons; lid retraction and proptosis.
- Most common cause of proptosis in adults, on one or both sides; can compress the optic nerve at the orbital apex.
- Idiopathic orbital inflammation (orbital pseudotumour): painful mixed inflammation and fibrosis without a cause; IgG4-related disease is a separate fibroinflammatory cause.
- Orbital lymphoma is usually extranodal marginal zone (MALT) lymphoma, sometimes with lacrimal gland involvement.
- Lacrimal gland: pleomorphic adenoma (benign) and adenoid cystic carcinoma (perineural spread, painful).
- Children: capillary hemangioma (infantile), dermoid cyst, rhabdomyosarcoma (embryonal type, rapid proptosis).

## What it is

The orbit is a bony cone with fixed volume, so swelling of its contents pushes the globe forward (proptosis) and can compress the optic nerve. The commonest cause in adults is thyroid-associated orbitopathy, in which autoimmune inflammation enlarges the extraocular muscles and orbital fat. Other inflammations include idiopathic orbital inflammation, IgG4-related disease, sarcoidosis and granulomatosis with polyangiitis; orbital cellulitis spreads from the sinuses. Tumours include lymphoma, lacrimal gland neoplasms, vascular lesions and, in children, rhabdomyosarcoma.

## Step by step

- Antibodies against the TSH receptor reach orbital fibroblasts, which also express it.
- Fibroblasts and T cells release cytokines; fibroblasts make hydrophilic glycosaminoglycans.
- Glycosaminoglycans bind water; muscles and fat swell.
- The globe is pushed forward and the eyelids retract.
- Crowding at the apex can compress the optic nerve; late fibrosis limits eye movements.

## Causes of proptosis

| Cause | Typical patient | Pathology |
| --- | --- | --- |
| [Thyroid-associated orbitopathy](https://durgical.com/en/conditions/thyroid-eye-disease/) | Adult with Graves disease | Swollen muscle bellies with glycosaminoglycans, lymphocytes, later fibrosis |
| [Orbital cellulitis](https://durgical.com/en/conditions/orbital-cellulitis/) | Child with sinusitis | Acute bacterial inflammation behind the septum |
| Idiopathic orbital inflammation | Adult, painful onset | Mixed inflammation and fibrosis |
| [IgG4-related disease](https://durgical.com/en/conditions/igg4-related-disease/) | Older adult, lacrimal swelling | IgG4 plasma cells, storiform fibrosis, obliterative phlebitis |
| [Granulomatosis with polyangiitis](https://durgical.com/en/conditions/granulomatosis-with-polyangiitis/) | Adult with sinus and kidney disease | Necrotising granulomatous vasculitis |
| [Orbital lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/) | Older adult, painless | Monoclonal B cells, often MALT type |
| Cavernous venous malformation | Middle-aged adult | Encapsulated dilated vascular channels |
| Rhabdomyosarcoma | Child, rapid onset | Small round cells with skeletal muscle markers |

## Clinical notes

- Smoking worsens thyroid-associated orbitopathy and should be stopped.
- Exposure of the cornea and compressive optic neuropathy are the threats to sight.

## Memory aid

A box with one open side: fill it with swollen muscle, pus or tumour and the eye is pushed out the front.

## Test yourself

Think of the answer, then tap the question to see it.

## Which part of the extraocular muscles is enlarged in thyroid-associated orbitopathy?

The muscle bellies, with the tendons spared, from glycosaminoglycan deposition and inflammation.

## What is the most common type of lymphoma in the orbit?

Extranodal marginal zone (MALT) lymphoma.

## Which malignant orbital tumour causes rapid proptosis in a child?

Rhabdomyosarcoma, usually the embryonal type.

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## Elsewhere in DurgiPedia

- [Proptosis and periorbital swelling](https://durgical.com/en/ophthalmology/proptosis-and-periorbital-swelling/)
- [The orbit, orbital septum and eyelids](https://durgical.com/en/ophthalmology/the-orbit-orbital-septum-and-eyelids/)
- [Type II hypersensitivity (antibody against cells)](https://durgical.com/en/immunology/type-ii-hypersensitivity/)

## Connections

## Related 6

- [Tumours of the eyelid and conjunctiva](https://durgical.com/en/general-pathology/tumours-of-the-eyelid-and-conjunctiva/)
- [Graves disease](https://durgical.com/en/general-pathology/graves-disease/)
- [ANCA-associated vasculitis](https://durgical.com/en/general-pathology/anca-associated-vasculitis/)
- [Marginal zone lymphomas](https://durgical.com/en/general-pathology/marginal-zone-lymphomas/)
- [Rhabdomyosarcoma](https://durgical.com/en/general-pathology/rhabdomyosarcoma/)
- [Benign vascular tumours](https://durgical.com/en/general-pathology/benign-vascular-tumours/)

## Related conditions 8

- [Thyroid eye disease (Graves orbitopathy)](https://durgical.com/en/conditions/thyroid-eye-disease/)
- [Graves disease (hyperthyroidism)](https://durgical.com/en/conditions/graves-disease/)
- [Orbital cellulitis](https://durgical.com/en/conditions/orbital-cellulitis/)
- [IgG4-related disease](https://durgical.com/en/conditions/igg4-related-disease/)
- [Granulomatosis with polyangiitis](https://durgical.com/en/conditions/granulomatosis-with-polyangiitis/)
- [Sarcoidosis](https://durgical.com/en/conditions/sarcoidosis/)
- [Non-Hodgkin lymphoma](https://durgical.com/en/conditions/non-hodgkin-lymphoma/)
- [Preseptal (periorbital) cellulitis](https://durgical.com/en/conditions/preseptal-cellulitis/)

[← All of general pathology](https://durgical.com/en/general-pathology/)

Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Graves Disease](https://www.ncbi.nlm.nih.gov/books/NBK448195/) (StatPearls (NCBI Bookshelf), 2026); [Orbital Cellulitis](https://www.ncbi.nlm.nih.gov/books/NBK507901/) (StatPearls (NCBI Bookshelf), 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/general-pathology/orbital-disease/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/general-pathology/orbital-disease/