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By

Dr. JUSUF FANTONI SpPA,MScPath(Glasg)

EYE PATHOLOGY

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EYE PATHOLOGY

Eyelid

The eyelid is a composite of skin externally and a mucosa

(the conjunctiva) on the surface opposed to the eye. Aside from

protecting the eye, elements within the eyelid generate critical

components of the tear film. Accessory lacrimal glands, eccrineand apocrine glands populate the eyelid. The sebaceous glands

( eis glands associated with the eyelash and the !eibomian

glands embedded within the eyelid fibrous tarsus ), which helps to

retard evaporation of tears. "f the drainage system of the sebaceous

glands is obstructed by chronic inflammation at the eyelid margin

(blepharitis ), or by neoplasm, then lipid may extravasate into

surrounding tissue and provoke a granuloamtous response # a lipo$

%ranuloma, or chalazion.

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Neoplasm

The most common malignancy of the eyelid is basal

cell carcinoma. The second is sebaceous carcinoma, not S

C C. Surprisingly, primary melanomas of the eyelid skinare extremely rare.

Eyelid neoplasms may distort tissue and prevent the

eyelids from closing completely. Exposure of the cornea is

not only painful, but also might predispose the patient tocorneal ulceration. B C C has a distinct predilection for the

lower eyelid and medial canthus.

Sebaceous carcinoma may mimic chalaion or may

diffusely thicken the eyelid.

Morphology

!n moderately differentiated or well"differentiated sebaceous

carcinoma, vacuoliation of the cytoplasm is present.

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!t may mimic B C C. #agetoid spread may mimic

Bowenoid actinic keratosis in the eyelid and carcinoma in situ in the

con$unctiva. Sebaceous carcinoma may spread through the con$unctival

epithelium and the epidermis to the lacrima drainage system and the

nasopharynx

Cornea

%nteriorly, the cornea is covered by epithelium that

rests on a basement membrane. Bowman&s layer, situated$ust beneath the epithelial basement membrane, is

acellular and forms an efficient barrier against the

penetration of malignant cells from the epithelium into the

underlying stroma.The corneal stroma lacks blood vessels and lymphatic

a featue that contributes to the transparancy of the

cornea.

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The corneal endotehlium is derived from neural crest

and is related to vascular endothelium.

'eratitis and ulcers(arious pathogens """ bacterial, fungal, viral ) especially

herpes simplex and herpes oster *, and protooal

) %canthamoeba* may cause corneal ulceration.

!n al forms of keratitis, dissolution of the corneal stromamay be accelerated by activationb of collagenenases within

corneal epithelium and stromal fibroblasts )+'eratocytes*.

eoplasms

The most common intraocular malignancy of adults is

metastasis to the uvea, typically to the choroid.

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The appearance of metastases to the eye is sugges"

tive of extremely short survival, and treatment of occular

metastases is usually palliative and delivered by radiation

therapy.

Ueal Ne! a"# Mela"omas

-veal melanoma is the most common primary intraocular

malignancy of adults. !ncidence increases with age. -nlike cutaneous

melanoma, the occurrence of uveal melanoma has remained stable

over many years. The etiology of uveal melanoma is unresolved at

this time.

There are no lymphatics within the eye, hence, uveal

melanomas, with very rare exception, spread exclusively by a

hematogenous route ) the only exception being the rare case of

melanoma that spreads through the sclera and invades the con$uctiva,

thereby gaining access to con$unctival klynmphatics *. ost uveal

mnelanomas spread first to the liver.

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$et!"a

/etinal eoplasms

$et!"o%lastoma

& the most common primary intraocular malignancy of children.

The cell of origin of retinoblastoma is neuronal. #rognosis is

adversely affected by extraocular extension and invasion along the

optic nerve and possibly by choroidal invasion.

/etinoblastom occurs in individuals who inherit a germ"line

mutation of one RB allele. /etinoblastomas arising in the context of

germ line mutations not only may be bilateral, but also may be

associated with pinealoblastoma ) so called 0 trilateral retinoblastoma*

Morphology

Tumors may contain both undifferentiated and differentiated

element. The former appear as collections of small, round cells with

hyperchromatic nuclei.

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!n well"differentiated tumors there 1lexner"2intersteiner

rosettes and fleurettes reflecting photoreceptor differentiation. !t should

be noted, however, that the degree of tumor differentiation does not

appear to be associated with the prognosis.

Tumor cells are encircling tumor blood vessels with onesof necrosis typically found in relatively avascular areas. This illustrates

graphically the dependance of retinoblastom on its blood supply.

/etinoblastom tends to spread to the brain and bone

marrow and seldom disseminates to the lungs.

% benign variant of retinoblastoma " retinocytoma "" has

been reported. The appearance of retinoblastoma in one eye and

retinocytoma in the other eye is characteristic of heritableretinoblastoma.