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Orbital lymphoma is a malignant lymphoid neoplasm involving the orbit, most commonly arising from extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma).
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It is the most common orbital malignancy in adults and typically presents as a painless, slowly progressive orbital mass.
| Feature | Details |
|---|---|
| Origin | Arises from mature B-cells, especially MALT-type in the orbit |
| Risk factors | – Chronic inflammation (e.g., Chlamydia psittaci infection, Sjögren's syndrome) |
| – Immunosuppression | |
| – Autoimmune disorders | |
| Systemic association | May be primary (limited to orbit) or secondary to systemic lymphoma |
Histological subtypes:
| Subtype | Frequency | Notes |
|---|---|---|
| Extranodal marginal zone (MALT) lymphoma | ~55–70% | Indolent course |
| Follicular lymphoma | ~20% | Intermediate grade |
| Diffuse large B-cell lymphoma (DLBCL) | ~10% | Aggressive |
| Mantle cell lymphoma | Rare | Often systemic |
Median age of presentation: ~60 years, slight female predominance
| Feature | Description |
|---|---|
| Painless orbital mass | Most common presentation |
| Proptosis | Unilateral or bilateral, slowly progressive |
| Eyelid swelling or fullness | Without erythema or tenderness |
| Diplopia | Due to mass effect on extraocular muscles |
| Visual disturbance | From compressive optic neuropathy (less common) |
| No signs of acute inflammation | Differentiates from IOI or orbital cellulitis |
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CT/MRI shows a homogeneous, well-marginated lesion, and definitive diagnosis requires biopsy.
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Common sites:
Imaging features:
| Modality | Imaging features |
|---|---|
| CT | • Soft tissue mass: Well-defined, homogeneous, mildly hyperdense relative to orbital fat |
| • Molding to orbital contours: No bone destruction; conforms to globe, extraocular muscles | |
| • No calcification or necrosis (unlike metastasis or infection) | |
| MR | • T1: Iso- to hypointense compared to muscle |
| • T2: Iso- to mildly hyperintense; less hyperintense than most other orbital lesions | |
| • Post-contrast: Homogeneous enhancement, no necrosis or cystic areas | |
| • DWI: Restricted diffusion is often present (useful for biopsy planning) |