Ophthalmic Pathology

NEOPLASTIC LESIONS OF EYELID SKIN

Xeroderma pigmentosa

●● Autosomal recessive defect in DNA repair system of body

●● Exposure to UV light can cause squamous cell carcinoma, basal cell carcinoma, malignant melanoma

Basal cell nevus syndrome (Gorlin-Goltz)

●● Affected individuals are prone to develop basal cell carcinoma of skin

Neurofibromatosis type I (NF-I)

NORMAL CONJUNCTIVA

●● Thin, movable mucus membrane lining inner surface of eyelids and sclera

eyelids ●● Bulbar conjunctiva lines surface of globe

INFLAMMATORY CONDITIONS OF CONJUNCTIVA

Chlamydia trachomatis

due to eyelashes ●● Leads to blindness

Ligneous conjunctivitis

●● All mucus membranes of body including conjunctiva, show subepithelial fibrin deposition

CONGENITAL ANOMALIES OF CONJUNCTIVA

Episcleral osseous choristoma

●● Represents embryonic rests of bone in episcleral tissue

●● Mature bone surrounded by mature fibrous tissue

Limbal dermoid

●● Solid choristoma mass with surface epithelium resembling epidermis, dermis, and adnexal structures

Neuronal ceroid lipofuscinosis

●● Neurodegenerative diseases showing accumulation of lipo-pigments within cells

bodies” on EM

Melanocytic abnormalities of conjunctiva

Hypermelanosis of conjunctiva

●● More than average number of typical melanocytes

Melanosis of episclera/scleral tissue/nevus of Ota

●● Risk factors for melanoma in ipsilateral uveal tract or deep orbital tissue

Melanocytic nevus of conjunctiva

●● Nevus associated with abnormal development of conjunctival epithelium

●● Solid nests of squamous cells/cysts lined by squamous epithelium, in substantia propria

●● Pleomorphic spindle shaped/epithelioid melanocytes

●● Melanocytes may occur in epithelium of inclusion cysts and mimic lymphatic spread of melanoma

Malignant melanoma of the conjunctiva

Squamous cell carcinoma of conjunctiva

NORMAL CORNEA

●● Outer protective coat located in center of anterior pole of eye

posterior): Non-keratinizing squamous epithelium, Bowman layer (acellular type I collagen), stroma, Descemet membrane (thick basement membrane of endothelial cells), and endothelium

SURGICAL PROCEDURES OF CORNEA

●● Various methods used to decrease corneal thickness

●● Photorefractive keratectomy and laser in situ keratomileusis (LASIK)

DEVELOPMENTAL ABNORMALITIES OF CORNEA

●● Microcornea: Horizontal diameter less than 9 mm at 1 year of age

●● Macrocornea: Horizontal diameter more than 11.5 mm at 1 year of age

from crystalline lens

INFLAMMATORY CONDITIONS OF CORNEA

Herpes simplex keratitis

●● After systemic body infection, HSV virus is retained in Gasserian ganglion

●● Virus periodically travels via sensory peripheral nerves to infect cornea

●● Linear branching ulcer of cornea (dendritic figure)

ation, foreign body granulomatous reaction

Acanthamoeba keratitis

●● Acanthamoeba is a protozoa found in soil and water

●● Invades cornea due to microabrasion of cornea, especially in contact lens wearers

DYSTROPHIC CONDITIONS OF CORNEA

●● Metabolic abnormalities of cornea that cause clinically detectable corneal opacities

Congenital hereditary endothelial dystrophy (CHED)

●● Opaque cornea due to edema, which is secondary to endothelial dystrophy

Map-dot-fingerprint dystrophy

●● Excessive production of basement membrane material by corneal epithelial cells

Fuchs endothelial dystrophy

drate cornea, and stroma becomes thick/ opaque

●● Descemet membrane thickened focally or diffusely

Keratoconus

●● Acquired localized stromal thinning of cornea, usually inferonasal quadrant

●● Abnormal activity of matrix metalloproteases, secreted by corneal keratinocytes

and scarring ●● Treated by penetrating keratoplasty

CORNEAL DEGENERATION

Band keratopathy

membrane ●● Marked vision loss

STRUCTURE OF CRYSTALLINE LENS

●● Lens develops from lens vesicle (derivative of surface ectoderm)

●● Anterior portion of vesicle composed of low columnar epithelium forming the anterior epithelium of adult lens

●● Posterior wall of vesicle composed of cells that lengthen substantially to form lens fibers

●● Succeeding fibers after cell division keep getting arranged in concentric layers

DEVELOPMENTAL ABNORMALITIES OF CRYSTALLINE LENS

Ectopia lentis

●● Dislocation of lens resulting from zonular rupture

drome (subluxates temporally and superiorly), homocystinuria (subluxates medially and inferiorly), and hyperlysinemia

STRUCTURE OF VITREOUS

●● Clear, gel-like structure (contains mostly water) that is found between lens and retina

●● Molecular constituents: Heterotypic collagens, glycosaminoglycans, and non-collagenous structural proteins

STRUCTURE OF OPTIC NERVE

●● Optic nerve is a tract of central nervous system and not a peripheral nerve

●● Refers only to anterior portion of the tract between retina and optic chiasm (50 mm in length)

●● Surrounded by dura, arachnoid, and pia mater

●● Nerve has organization similar to white matter of the brain

●● Axonal fibers surrounded by oligodendrocytes and not Schwann cell sheaths

STRUCTURE OF ORBIT

nerves, and connective tissue

lacrimal, maxillary, palatine, sphenoid, and zygomatic bones

●● Optic nerve, ophthalmic artery, and sympathetic nerves transmitted from posterior orbit through optic foramen to middle cranial fossa

Lesions of orbit

Dermoid cyst

●● Cystic choristoma containing benign dermal elements

●● Lined by keratinized stratified squamous epithelium

Epidermoid cyst

Langerhans cell histiocytosis (LCH)

Lymphangioma

lymphocytes ●● Stain positively with D2-40 immunostain

Inflammatory pseudotumor of orbit

●● Pleomorphic inflammation (predominance of plasma cells)

Tumors of lacrimal gland

●● Most common tumor is pleomorphic adenoma

●● Most common malignant tumor is adenoid cystic carcinoma

STRUCTURE OF EYE

●● Two functional compartments of eye are anterior segment and posterior segment

●● Anterior segment includes two fluid chambers: Anterior chamber and posterior chamber

●● The two chambers are divided by iris and communicate via pupil

●● Aqueous humor is a transparent fluid that fills both chambers (formed by ciliary body)

Posterior segment

MAJOR ANOMALIES OF EARLY DEVELOPMENT

Cyclopia

●● Consequence of development of single optic vesicle

above the fused/single globe

Synophthalmus

●● Less severe condition resulting from fusion of paired optic vesicles

●● Eyes are relatively well differentiated in anterior segment

Anophthalmos

Microphthalmos

Nanophthalmos

Cryptophthalmos (ablepharon)

by skin ●● Skin is continuous from eyebrows to cheek

Primary aphakia

tion of vesicle

Coloboma

embryonic week ●● Atypical colobomas occur in regions other

than inferonasal area ●● Cystic coloboma (associated with microph-

thalmos) results from faulty closure of optic fissure and imperfect alignment of optic vesicle walls

●● Coloboma of lens is secondary to coloboma of ciliary body (region of absence of zonules)

RETINOBLASTOMA

●● Most common primary intraocular neoplasm of children

●● Clinical presentation with leukocoria and/ or strabismus

brain ●● Growth pattern in eye; endophytic/

exophytic/diffusely infiltrating ●● Small, round, undifferentiated retinoblas-

toma cells with hyperchromatic nuclei and scant cytoplasm

●● Flexner-Wintersteiner rosettes, HomerWright rosettes, pseudorosettes, and fleurettes

invasion of the optic nerve; bad prognosis ●● Retinoblastoma gene (RB gene); tumor sup-

pressor gene, located at 13q14 ●● Loss/inactivation of both normal alleles of

RB gene

●● Sporadic retinoblastoma arises from two somatic mutations in the same cell; “two hit hypothesis of Knudson”

Spontaneously regressed retinoblastoma

●● Clinically seen in “unaffected” family members of a newly diagnosed patient

Trilateral retinoblastoma

with bilateral retinoblastoma

MEDULLOEPITHELIOMA

epithelium ●● May be benign or malignant ●● Interlacing sheets, cords, and rosettes of

medullary epithelium ●● Intraocular extension in malignant forms ●● Teratoid medulloepitheliomas contain

heterotopic elements

MALIGNANT MELANOMA

OPTIC NERVE GLIOMA

stroma ●● Rosenthal fibers ●● Surgical resection of optic nerve/

enucleation

MENINGIOMA OF OPTIC NERVE

ORBITAL RHABDOMYOSARCOMA

METASTATIC TUMORS

●● Acute leukemia, myeloid sarcoma (may be bilateral and cause proptosis)

●● Burkitt lymphoma, neuroblastoma, Ewing sarcoma

●● Buphthalmos; enlarged eye with raised intraocular pressure

●● Ruptures in Descemet membrane, corneal edema, cupping of the optic nerve

●● Developmental (congenital/infantile) glaucoma may be primary or secondary

PRIMARY

SECONDARY

●● Associated with other ocular or systemic disorders

ease): Cherry red spot in the retina

OCULAR TRAUMA

●● Neural retinal hemorrhages (splinter, flame shaped, blob); newborns due to mechanical rise in pressure of skull during labor/ obstetrical instrumentation

●● Tears in Descemet membrane due to obstetric forceps

●● Hemorrhages in vitreous and subdural area of optic nerve, conjunctiva and lid

●● Retinal trauma: Tears, detachments, schisis, and folds

●● Most ruptures found at corneal sclera limbus (thin region)

SYMPATHETIC OPHTHALMIA

●● Bilateral granulomatous inflammation of uveal tract

●● Appears 5 days to many years following trauma to one/both eyes

PHTHISIS BULBI

●● Eye condition occurring months to years following trauma

zation, fibrosis, and calcification