Diseases of the
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Diseases of the orbit present with
displacement of the eye (proptosis) or orbital pain.
The main causes for
swelling in the orbit are vascular lesions, inflammatory diseases, and tumours.
Clinical evaluation includes imaging of the orbit to establish the site and
nature of the swelling, followed by biopsy in many cases.
(Graves disease) may cause orbital swelling and proptosis due to accumulation of
extracellular matrix material in the orbital tissues.
Disease of the orbit may be manifest by displacement of the eye.
Imaging of the orbit is an important part of ivestigation of proptosis.
case swelling of orbital tissues suggests thyroid eye disease.
Lymphoma is the most common type of primary malignant orbital tumour
The most common primary tumour of the orbit is non-Hodgkin's lymphoma. The
majority are low-grade B-cell lymphoplasmacytic tumours; less common are
high-grade centroblastic/immunoblastic tumours. Burkitt's lymphoma, a high-grade
lymphoblastic B-cell tumour, is the most common orbital tumour in some parts of
Macroscopically, tumours form masses within the orbit, often involving the
extraocular muscles. Many arise from the lacrimal gland.
Tumours that are of the low-grade lymphoplasmacytic type have a low risk (<25%)
of systemic disease and an excellent prognosis, whereas those that are
intermediate- or high-grade have a high risk (>60%) of developing systemic
Benign reactive lymphoid infiltrates of the orbit are also seen and must be
distinguished from lymphomas by immunohistochemistry.
Orbital tumours of mesodermal and neural origin may be benign or malignant
Orbital tumours may arise from neural or mesodermal tissues. Different tumours,
both benign and malignant, are encountered in different age groups.
Ocular tumour extension into the orbit is a frequent development, the main
ocular tumours being retinoblastoma in childhood, and uveal melanoma in adults.
Rhabdomyosarcoma of the orbit is a tumour of childhood, being of the embryonal
sub-type. Although highly malignant, treatment with radiotherapy and
chemotherapy shows a 3-year survival rate of 93%.
Fibrous histiocytoma is the most common mesenchymal tumour of the orbit in
adults. It is a spindle-cell tumour composed of fibroblast-like cells and
histiocyte-like cells with a collagenous matrix, classified into benign, locally
aggressive, and malignant types. As they are poorly circumscribed, these tumours
often recur, with a recurrence rate of 30% for benign lesions, 57% for locally
aggressive lesions, and 64% for malignant lesions.
Fibro-osseous lesions from the skull often encroach on the orbit, particularly
fibromatoses, primary bone tumours, fibrous dysplasia of bone, and Langerhans
cell histiocytosis (histiocytosis X).
Benign nerve-sheath tumours account for about 2% of all orbital tumours. They
are either well-circumscribed schwannomas (neurilemmomas) or less easily excised
Meningiomas of the orbit arise from the arachnoidal meningothelial cells of the
optic nerve sheath and are similar to those that occur in the CNS.
Optic-nerve gliomas are astrocytomas of low-grade malignancy, classed as
juvenile pilocytic astrocytomas. Histologically they are spindle-cell tumours
with a fine fibrillarity.
Lacrimal gland swellings may be inflammatory or neoplastic
Enlargement of lacrimal gland may be due to specific or non-specific
inflammation (including granulomatous diseases), or to primary (benign and
malignant) and metastatic neoplasms.
Infection (commonly due to bacteria) of the lacrimal gland or ducts may cause
swelling. Blockage of the duct may occur with local overgrowth of Actinomyces,
forming the basis for a calculus composed of filamentous organisms.
Cysts of the lacrimal gland or associated ducts are common. Some are
developmental dermoid cysts, whereas others are retention cysts caused by duct
Sjِgren's disease is associated with autoimmune infiltration and enlargement of
the gland by lymphoid cells, with gland loss causing dry eyes.
Sarcoidosis is associated with expansion of the gland by non-caseating
Lymphoma of the lacrimal gland is the most common primary tumour (usually
low-grade B-cell non-Hodgkin's lymphoma).
Epithelial tumours of the lacrimal gland are histologically similar to those of
the salivary glands, the main types being pleomorphic adenoma, adenoid cystic
carcinoma, carcinoma in a pleomorphic adenoma (malignant mixed tumour) and, less
commonly, squamous carcinoma and adenocarcinoma.
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