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OP2.7-8 | Orbital Tumours: Classification, Presentation, Workup and Referral — SDL Guide

Learning Objectives

• Classify orbital tumours by origin (primary, secondary, metastatic), biological behaviour (benign, malignant), patient age, and tissue of origin
• Describe the clinical presentation of major orbital tumours including capillary haemangioma, dermoid, rhabdomyosarcoma, cavernous haemangioma, optic nerve glioma, optic nerve sheath meningioma, lacrimal gland tumours, orbital lymphoma, and metastases
• Select appropriate investigations for an orbital tumour, including CT and MRI orbit with their specific indications, and systemic workup for lymphoma and metastatic disease
• Explain why incisional biopsy is contraindicated for suspected lacrimal gland pleomorphic adenoma
• Outline the management of major orbital tumours and enumerate the red flag features that indicate urgent referral

INSTRUCTIONS

The orbit contains structures from almost every tissue type — vascular, neural, epithelial, lymphoid, and connective — and tumours can arise in any of them. A systematic classification framework is therefore the clinician's most important tool: it converts an overwhelming list of names into a logical structure that guides clinical assessment, imaging choices, and management decisions. This module takes you through the major orbital tumours systematically, with emphasis on the clinical and imaging features that distinguish them and the management decisions — particularly biopsy choices and referral thresholds — that determine patient outcomes.

References

• Khurana AK. Comprehensive Ophthalmology, 7th ed. Chapter on Diseases of the Orbit (textbook)
• Parsons' Diseases of the Eye, 23rd ed. Chapter on Orbital Tumours (textbook)

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Version 2.0 | NMC CBUC 2024

A Lump Behind the Eye: Recognising Orbital Tumours

An orbital tumour is any neoplastic or tumour-like mass arising within the orbit or extending into it from adjacent structures. The clinical presentation is dominated by the consequences of a space-occupying lesion in a rigid bony compartment — but the presenting symptom depends critically on the tumour's location, rate of growth, and biological behaviour.

The most common presenting symptom is proptosis — forward displacement of the globe that the patient or a relative notices. However, several features of the proptosis provide immediate diagnostic information, because orbital tumours are not a homogeneous group — they range from benign hamartomas of childhood (capillary haemangioma) to aggressive malignancies (rhabdomyosarcoma, lacrimal gland adenoid cystic carcinoma) with fundamentally and clinically different urgency of workup and treatment:

• Time course: Slow and painless over months to years suggests a benign lesion (cavernous haemangioma, lacrimal gland pleomorphic adenoma, optic nerve meningioma). Rapid progression over days to weeks, especially in a child, raises the possibility of rhabdomyosarcoma or acute haemorrhage into a lymphangioma. In adults, rapid onset may indicate orbital metastasis, lymphoma, or inflammatory orbital pseudotumour.
• Direction: Axial proptosis (no lateral displacement) indicates an intraconal mass. Eccentric proptosis (globe displaced inferiorly, medially, or laterally) indicates the location of the extraconal mass opposite the direction of displacement.
• Pain: Most benign orbital tumours are painless. Pain is a red flag suggesting malignancy with periosteal invasion, acute inflammatory change, or adenoid cystic carcinoma of the lacrimal gland (characterised by perineural spread and severe pain).
• Diplopia: Extraocular muscle restriction from mass effect, infiltration, or mechanical tethering.
• Visual loss: Compressive optic neuropathy (axial intraconal lesion), optic nerve infiltration (glioma, meningioma), or exposure keratopathy.

The hook cases — the 40-year-old woman with three years of painless axial proptosis and the 6-year-old boy with 2 weeks of rapid eccentric proptosis — represent the two ends of the spectrum. The woman's history and CT are classic for cavernous haemangioma (well-defined intraconal mass, no bony destruction, slow growth). The boy's presentation — rapidly progressive proptosis in a child, eccentric, with bone remodelling — is rhabdomyosarcoma until proved otherwise, a paediatric oncological emergency.

Clinical Presentation by Tumour Type

Each major orbital tumour has a characteristic clinical signature — a combination of age, time course, location, and associated features that, taken together, often allows a clinical diagnosis before imaging. The following descriptions use this clinical signature approach.

Capillary haemangioma: Presents in the first months of life; the commonest orbital vascular tumour of infancy. The lesion is a bright red, lobulated, compressible mass, superficial (in the lid or anterior orbit) or deep. Its critical features are: it enlarges with crying or Valsalva manoeuvre (because increased venous pressure engorges its thin-walled capillaries), and it spontaneously involutes by age 7–10 years. Treatment is indicated only if the lesion threatens vision by causing amblyopia (anisometropic from induced astigmatism, or deprivation from obscuring the visual axis). First-line treatment when required: oral propranolol (β-blocker, causes vasoconstriction and reduced VEGF expression in the haemangioma endothelium).

Dermoid cyst: A congenital choristoma occurring along cranial suture lines — most commonly the frontozygomatic suture (superolateral orbit, most common site) and frontolacrimal suture (superomedial). It presents in childhood as a firm, non-tender, smooth swelling that may not be noticed until school age. It does not transilluminate. The critical clinical hazard is rupture — spontaneous or traumatic — which releases keratin and sebum into the orbit, causing an intense granulomatous inflammatory reaction mimicking orbital cellulitis. Management: elective surgical excision before rupture.

Rhabdomyosarcoma: The commonest primary orbital malignancy in children, typically presenting in the first decade of life. It is a rapidly progressive extraconal mass, most commonly in the superior orbit, causing downward and forward globe displacement with periorbital oedema and sometimes bruising that can mimic trauma or orbital cellulitis. The embryonal subtype is most common in the orbit. Absence of fever does not exclude it. This is the orbital tumour in a child that must NEVER be delayed — a biopsy is required urgently under general anaesthetic.

Cavernous haemangioma: The commonest benign orbital tumour in adults. It is a slow-growing, well-encapsulated, intraconal mass, most commonly in the right orbit for reasons that are unexplained. The presenting symptom is axial proptosis progressing over years with no pain. The patient's visual acuity is typically preserved until the mass compresses the optic nerve at the orbital apex. On imaging, MRI shows a T1-isointense, T2-bright, well-defined lesion with characteristic progressive fill-in enhancement on dynamic gadolinium imaging — the most diagnostically useful MRI feature.

Optic nerve glioma: A pilocytic astrocytoma of the optic nerve, predominantly in childhood; approximately 30–50% of childhood orbital optic nerve gliomas are associated with neurofibromatosis type 1 (NF-1). Presents with axial proptosis, relative afferent pupillary defect (RAPD), and visual loss — the combination of axial proptosis and visual field defect strongly suggests an optic nerve lesion. MRI shows fusiform T2-bright expansion of the optic nerve with no sharp nerve-tumour boundary.

Optic nerve sheath meningioma: Arises from the meningeal arachnoid cells sheathing the optic nerve; predominantly in adult women in the 4th–5th decade. Its hallmark presentation is visual loss disproportionate to the degree of proptosis — the meningioma compresses the nerve as it grows, causing progressive optic atrophy before proptosis becomes marked. Optociliary shunt vessels — retinociliary collateral veins visible on fundoscopy at the disc margin — are pathognomonic of chronic optic nerve sheath compression. CT shows 'tram-track' calcification along the nerve; MRI shows circumferential 'tram-track' enhancement around the nerve with gadolinium.

Lacrimal gland tumours: The lacrimal gland in the superolateral orbit produces two clinically distinct presentations:
- Pleomorphic adenoma (benign mixed tumour): Slow-growing (months to years), painless, smooth, non-tender; produces characteristic S-shaped ptosis (the upper lid curves downward at its lateral aspect) and inferomedial globe displacement. CT shows a well-defined mass expanding (remodelling, not eroding) the lacrimal fossa. Incisional biopsy is contraindicated — it seeds the tumour into the orbit and transforms a curable tumour into an incurable, recurrent, eventually malignant lesion. Management: planned total en bloc excision with intact capsule.
- Adenoid cystic carcinoma (malignant lacrimal gland tumour): Presents with onset over months, pain (due to perineural invasion — the pathological hallmark of this tumour), irregular border, and bone erosion on imaging. It is the commonest malignant lacrimal gland tumour and carries a poor prognosis because of its propensity for perineural spread to the cavernous sinus and skull base.

Orbital lymphoma: Almost always B-cell non-Hodgkin lymphoma — the commonest type is extranodal MALT lymphoma (mucosa-associated lymphoid tissue), which is low-grade and may present as a unilateral or bilateral 'salmon-pink' subconjunctival mass that is soft and moulded to the globe. Orbital lymphoma can present in isolation or as part of systemic lymphoma. Systemic staging is always required.

Orbital metastases: Haematogenous spread from a distant primary. Breast is the commonest source in women — notably, scirrhous (fibrotic) breast metastases cause enophthalmos (sunken eye) rather than proptosis, because the fibrotic process actually contracts the orbit. Lung is the commonest source in men. Prostate and kidney are less common in adults. In children, neuroblastoma (adrenal primary) classically metastasises to the orbit, producing bilateral periorbital bruising ('panda eyes' or 'raccoon eyes').

MRI Comparison of Common Orbital Masses

Classification of Orbital Tumours

Understanding orbital tumour classification is not a memory exercise — it is the cognitive scaffolding that allows a clinician to generate a differential diagnosis from first principles at the bedside, before CT results are available. The orbit is embryologically complex, incorporating mesenchymal, ectodermal, neural crest, and vascular tissue; each tissue type gives rise to a distinct family of tumours with characteristic clinical behaviour, imaging appearances, and management. Children and adults have fundamentally different orbital tumour spectrums: in children, the most common primary orbital tumour is the capillary haemangioma (benign, involutes spontaneously) but the most feared is rhabdomyosarcoma (rapidly fatal if untreated); in adults, lymphoma and lacrimal gland carcinoma predominate among primary tumours, while metastasis from breast, lung, and prostate is the most common malignant cause overall.

Provided image

A systematic four-axis classification transforms the daunting list of orbital tumour names into a logical structure that guides clinical decision-making.

Axis 1: Origin
- Primary orbital tumours: Arise from tissues native to the orbit. Include the full range of histological types — vascular (capillary haemangioma, cavernous haemangioma, lymphangioma, orbital varices), neural (optic nerve glioma, optic nerve sheath meningioma, schwannoma, neurofibroma), lacrimal gland (pleomorphic adenoma, adenoid cystic carcinoma, other epithelial tumours), lymphoid (orbital lymphoma — MALT, diffuse large B-cell), and mesenchymal (rhabdomyosarcoma, fibrous histiocytoma).
- Secondary orbital tumours (direct extension): Arise outside the orbit and extend into it through bony walls. Sources: sinuses (frontal, ethmoid, maxillary — squamous cell carcinoma, mucocele, adenocarcinoma); eyelids (sebaceous gland carcinoma, squamous cell carcinoma); globe (uveal melanoma through sclera, retinoblastoma).
- Metastatic tumours: Reach the orbit by haematogenous spread. Breast (most common overall, and specifically the commonest source in women), lung (most common in men), prostate, kidney, neuroblastoma (children).

Axis 2: Biological behaviour
- Benign: Well-circumscribed, non-invasive, no bony erosion, remodel rather than destroy bone, slow growth, no distant metastasis. Examples: cavernous haemangioma, dermoid, lacrimal gland pleomorphic adenoma, optic nerve glioma (pilocytic astrocytoma in children = benign histologically).
- Malignant: Infiltrative, bone-eroding, fast-growing, metastatic potential. Examples: rhabdomyosarcoma, adenoid cystic carcinoma, diffuse large B-cell lymphoma, metastases.

Axis 3: Patient age
- Childhood orbital tumours: Capillary haemangioma (infancy), dermoid cyst (childhood), rhabdomyosarcoma (first decade — malignant, urgent), optic nerve glioma (first two decades, NF-1), lymphangioma (childhood), neuroblastoma metastasis (first decade, bilateral periorbital bruising).
- Adult orbital tumours: Cavernous haemangioma (4th–5th decade), lacrimal gland tumours (4th–6th decade), optic nerve sheath meningioma (4th–5th decade, predominately women), orbital lymphoma (5th–7th decade), metastases (5th–7th decade), thyroid eye disease (note: not in this classification as it is not a tumour, but must always be in the adult bilateral proptosis differential).

Axis 4: Tissue of origin — tissue-based grouping

Tissue type	Benign	Malignant
Vascular	Capillary haemangioma, cavernous haemangioma, orbital varices	Haemangiopericytoma
Neural	Optic nerve glioma (childhood), schwannoma, neurofibroma	Optic nerve sheath meningioma (locally aggressive), malignant peripheral nerve sheath tumour
Lacrimal gland	Pleomorphic adenoma	Adenoid cystic carcinoma, mucoepidermoid carcinoma
Lymphoid	Benign reactive lymphoid hyperplasia	MALT lymphoma, diffuse large B-cell lymphoma
Mesenchymal	Dermoid cyst, fibrous dysplasia	Rhabdomyosarcoma
Secondary / metastatic	—	Sinus carcinoma extension, breast/lung/prostate metastases, neuroblastoma (children)