Ординатура / Офтальмология / Английские материалы / Ocular Pathology_6th edition_Yanoff, Sassani_2009

A

C

1.Glaucoma is often present.

2.The condition may be an isolated finding or may be associated with neurofibromatosis, facial hemihypertrophy, peripheral corneal dysgenesis, or the

Prader–Willi syndrome (approximately 1% of patients with Prader–Willi syndrome, a chromosome 15q deletion syndrome, have oculocutaneous albinism).

Histologically, flattened iris pigment epithelium lines the anterior surface of the involved iris, which may show increased neovascularization.

B.The more common form, acquired ectropion, is acquired and progressive, usually a result of iris neovascularization.

Peripheral Dysgenesis of the Cornea and Iris

See pp. 262–264 in Chapter 8.

Coloboma

I. A coloboma (i.e., localized absence or defect) of the iris may occur alone or in association with a coloboma of the ciliary body and choroid (Fig. 9.8; see also Fig. 2.9).

B

Fig. 9.7 Congenital ectropion uveae. A, At 6 months of age, infant was noted to have abnormal left eye. Here, at 8 years of age, child has normal right eye, but lighter left eye with ectropion uveae, B, and glaucoma. Filtering procedure was performed. C, Histologic section of iridectomy specimen shows a pigmented anterior iris surface. Case was previously mistakenly reported as iridocorneal endothelial syndrome. (Case #7 in Scheie HG, Yanoff M: Arch Ophthalmol 93:963, 1975. © American Medical Association. All rights reserved.)

A.Typical colobomas occur in the region of the embryonic cleft, inferonasally, and may be complete, incomplete

(e.g., iris stromal hypoplasia; see Fig. 9.6A), or cystic in the area of the choroid.

B.Atypical colobomas occur in regions other than the inferonasal area.

C.Typical colobomas are caused by interference with the normal closure of the embryonic cleft, producing defective ectoderm.

The anterior pigment epithelium seems primarily to be defective. Except in the rare iris bridge coloboma, no tissue spans the defect. Iridodiastasis is a coloboma of the iris periphery that resembles an iridodialysis. In the ciliary body, mesodermal and vascular tissues that fill the region of the coloboma often underlie the pigment epithelial defect. The ciliary processes on either side of the defect, however, are hyperplastic. The mesodermal tissue may contain cartilage in trisomy 13 (see Fig. 2.9). Zonules may be absent so that the lens becomes notched, producing the appearance of a coloboma of the lens. The retinal pigment epithelium (RPE) is absent in the area of a choroidal coloboma but is usually hyperplastic at the edges. The neural retina is atrophic and gliotic and may contain rosettes. The choroid is partially or completely absent. The sclera may be thin or ectatic, sometimes appearing as a large cyst (see subsection Microphthalmos with Cyst, p. 531 in Chapter 14).

B

II.The extent of a coloboma of the choroid varies.

A.It may be complete from the optic nerve to the ora serrata inferonasally.

B.It may be incomplete and consist of an inferior crescent at the inferonasal portion of the optic nerve.

C.It may consist of a linear area of pigmentation or RPE and choroidal thinning in any part of the fetal fissure.

III.Colobomas may occur alone or in association with other ocular anomalies.

About 8% of eyes with congenital chorioretinal coloboma contain a retinal or choroidal detachment.

IV. The condition may be inherited as an irregular autosomaldominant trait.

V.Histology

A.The iris coloboma shows a complete absence of all tissue in the involved area; a complete sector from pupil to periphery may be involved, or only a part of the iris.

Iris coloboma is often associated with heterochromia iridum.

B.The ciliary body coloboma shows a defect filled with mesodermal and vascular tissues (also cartilage in

trisomy 13) with hyperplastic ciliary processes at the edges.

C.The choroidal coloboma shows an absence or atrophy of choroid and an absence of RPE with atrophic and gliotic retina, sometimes containing rosettes.

1.The RPE tends to be hyperplastic at the edge of the defect.

2.The sclera in the region is usually thinned and may be cystic; the cystic space is often filled with proliferated glial tissue.

The proliferated glial tissue may become so extensive (i.e., massive gliosis) as to be confused with a glial neoplasm.

Cysts of the Iris and Anterior Ciliary Body

(Pars Plicata)

I.Iris stromal cysts (Figs 9.9 and 9.10) resemble implantation iris cysts after nonsurgical or surgical trauma.

A.The cysts can become quite large and cause vision problems by impinging on the pupil; they may also occlude the angle and cause secondary closed-angle glaucoma.

Echographic evaluation can accurately document the location, size, and internal structure of primary cysts of the iris pigment epithelium. Ultrasonographic biomicroscopy has shown that approximately 54% of “normal” patients may have asymptomatic ciliary body cysts.

B.The origin of the cysts is poorly understood, although evidence suggests a two-part derivation: a component from cells of the iris stroma and an epithelial component from nonpigmented neuroepithelial cells.

Rarely, an occult, intrauterine limbal perforation of the anterior chamber with a needle may occur during amniocentesis.

C.Histologically, the cysts are lined by a multilayered epithelium resembling corneal or conjunctival epithelium, which may even have goblet cells. The cysts usually contain a clear fluid, and may be surrounded by a layer of epithelium.

II.Iris or ciliary body epithelial cysts are associated with the nonpigmented epithelium of the ciliary body or the pigmented neuroepithelium on the posterior surface of the iris or at the pupillary margin.

A.With the possible exception of the development of a secondary closed-angle glaucoma or pupillary obstruction, the clinical course of the pigment epithelial cysts is usually benign.

Multiple iris and ciliary body pigment epithelial cysts may be found in congenital syphilis. Secondary closed-angle glaucoma frequently develops in these eyes. Rarely, plateau iris can be caused by multiple ciliary body cysts.

B.The cysts form as the posterior layer of iris pigment epithelium or the inner layer of ciliary epithelium proliferates.

Occasionally, a cyst may break off and float in the anterior chamber. The cyst may then implant in the anterior-chamber

A

C

angle, where it has on occasion been mistaken for a malignant melanoma. The cyst may also float freely, enlarge, and so obstruct the pupil that surgical removal of the cyst is necessary.

III.Histologically, the pigmented cysts are filled with a clear

fluid and are lined by epithelial cells having all the characteristics of mature pigment epithelium.

Cysts of the Posterior Ciliary Body (Pars Plana)

I. Most cysts of the pars plana (Fig. 9.11) are acquired.

II.Pars plana cysts lie between the epithelial layers and are analogous to detachments (separations) of the neural retina.

Clinically, the typical pars plana cysts and those of multiple myeloma appear almost identical. With fixation, however, the multiple myeloma cysts turn from clear to white or milky (see

Fig. 9.11E and F), whereas the other cysts remain clear. The multiple myeloma cysts contain γ-globulin (immunoglobulin). Cysts similar to the myeloma cysts but extending over the pars plicata

B

Fig. 9.10 A, Gross specimen shows clear cyst of pars plicata of ciliary body. B, Scanning electron micrograph of nonpigmented ciliary epithelial cyst present at anterior margin of pars plicata. C, Proliferating nonpigmented epithelial cells in cyst wall. Note thin basement membrane on one side (arrow) and poorly formed multilaminar basement membrane on the other. (A and B, Courtesy of

Dr. RC Eagle, Jr.)

have been seen in nonmyelomatous hypergammaglobulinemic conditions.

III.Histologically, large intraepithelial cysts are present in the pars plana nonpigmented ciliary epithelium.

T e nonmyelomatoush cysts appear empty in routinely stained sections but are shown to contain a hyaluronidasesensitive material—hyaluronic acid—when special stains are used to demonstrate acid mucopolysaccharides.

INFLAMMATIONS

See Chapters 3 and 4.

INJURIES

See Chapter 5.

SYSTEMIC DISEASES

Cystinosis

See p. 299 in Chapter 8.

See sections Iris and Ciliary Body and Choroid in Chapter 15.

See p. 385 in Chapter 10.

Juvenile Xanthogranuloma (Nevoxanthoendothelioma)

I.Juvenile xanthogranuloma ( JXG), one of the non-Langer- hans’ cell histiocytoses (Fig. 9.12; see also Fig. 1.18), is a benign cutaneous disorder of infants and young children.

A.The typical raised orange-skin lesions occur singly or in crops and regress spontaneously.

Solitary spindle-cell xanthogranuloma (SCXG), another of the non-Langerhans’ cell histiocytoses, may involve the eyelids and contains Touton giant cells, but differs from JXG in containing more than 90% spindle cells. SCXG may be an early form of JXG.

B.The skin lesions may predate or postdate the ocular lesions, or occur simultaneously.

II.Ocular findings include di use or discrete iris involvement

(most common ocular finding), but occasionally ciliary

body and anterior choroidal lesions, epibulbar involvement, corneal lesions, nodules on the lids, and orbital granulomas may be seen.

A.Most ocular lesions occur unilaterally in the very young, most under 6 months of age.

Rarely, a limbal nodule can occur in an adult.

B.The iris lesions are quite vascular and bleed easily.

When confronted with an infant who has a spontaneous hyphema, the clinician must consider JXG along with retinoblastoma (iris neovascularization here can cause bleeding into the anterior chamber) and trauma (the parents may think that the hemorrhage was spontaneous, but unknown trauma could have caused it).

III.JXG is separate from the group of nonlipid reticuloendothelioses called Langerhans’ granulomatoses or histiocytosis X

(eosinophilic granuloma, Letterer–Siwe disease, and Hand–Schüller–Christian disease; see discussion of reticuloendothelial system in subsection Primary Orbital Tumors in Chapter 14).

IV. Histologically, a di use granulomatous inflammatory reaction with many histiocytes and often with Touton giant cells is seen.

A.Often the lesions are vascular.

B.Touton giant cells may also be found in necrobiotic xanthogranuloma and liposarcoma.

JXG may be confused histologically with necrobiosis lipoidica diabeticorum, granuloma annulare, erythema induratum, atypical sarcoidosis, Erdheim–Chester disease, Rothman–Makai panniculitis, foreign-body granulomas, various xanthomas, nodular tenosynovitis, and the extra-articular lesions of proliferative synovitis.

Mucopolysaccharidoses

See p. 298 in Chapter 8.

ATROPHIES AND DEGENERATIONS

See subsections Atrophy and Degeneration and Dystrophy in Chapter 1.

Iris Neovascularization (Rubeosis Iridis)

See Figures 9.13 and 9.14; see also Fig. 15.5.

The term rubeosis iridis means “red iris” and should be restricted to clinical usage; iris neovascularization is the proper histopathologic term.

6.Retinal vascular disease

7.Ocular ischemic syndrome

B.Neoplastic

1.Uveal malignant melanoma

2.Retinoblastoma

3.Metastatic carcinoma (uveal)

4.Embryonal medulloepithelioma

5.Metastatic tumors

C.Inflammatory

1.Chronic uveitis (e.g., Fuchs’ heterochromic iridocyclitis)

2.Post retinal detachment surgery

3.Postradiation therapy

4.Fungal endophthalmitis

5.Posttrauma (surgical or nonsurgical)

D.Neural retinal diseases

1.Diabetes mellitus (usually only in advanced diabetic retinopathy)

2.Chronic neural retinal detachment

3.Coats’ disease

4.Chronic glaucoma (almost never with primary chronic open-angle glaucoma unless surgical trauma or central retinal vein occlusion has occurred)

5.Sickle-cell retinopathy

6.Retinopathy of prematurity

7.Eales’ disease

8.Persistent hyperplastic primary vitreous

9.Leber’s miliary microaneurysms

10.Norrie’s disease

II.Iris neovascularization may be induced by hypoxia, by products of tissue breakdown, or by a specific angiogenic factor. Neovascularization of the iris is always secondary to any of a host of ocular and systemic disorders.

III.Neovascularization often starts in the pupillary margin and the iris root concurrently, but can start in either place first; the mid stromal portion is rarely involved early.

Early iris neovascularization in the angle does not cause synechiae and a closed angle but rather a secondary open-angle glaucoma, owing to obstruction of outflow by the fibrovascular membrane. Synechiae are rapidly induced, and chronic secondary closedangle glaucoma ensues. Rarely, however, the rubeosis iridis involves the angle structures and anterior iris surface without causing synechiae, as may occur in Fuchs’ heterochromic iridocyclitis.

IV. A secondary closed-angle glaucoma (called neovascular glaucoma) and hyphema are the main complications of iris neovascularization.

Occasionally, iris neovascularization may be difficult to differentiate from normal iris vessels, especially when iris vessels are dilated secondary to ocular inflammation. Even with such dilatation, however, the normal iris vessels are seen to course radially, in contrast to the random distribution found in iris neovascularization. Fluorescein angiography can be helpful in differentiating normal from abnormal iris vessels by demonstrating leakage from the abnormal vessels.

V.Histologically, fibrovascular tissue is found almost exclusively on the anterior surface of the iris and in the anteriorchamber angle.

A.The blood vessels, however, are derived initially from the ciliary body near the iris root or from iris stromal blood vessels.

B.The new vascular growth seems to leave the iris stroma rapidly (most commonly toward the pupil) to grow on and over the anterior surface of the iris.

With contracture of the myoblastic component of the fibrovascular tissue, the pupillary border of the iris is turned anteriorly (ectropion uveae). Synechiae are characteristically only present in the area of the anterior-chamber angle peripheral to the end of Descemet’s membrane. They can be differentiated, therefore, from such broad-based synechiae as may be caused by a persistent flat chamber, chronic closed-angle glaucoma, or iris bombé.

Choroidal Folds

I.The condition consists of lines, grooves, or striae, often arranged parallel and horizontally. Occasionally the folds may be vertical, oblique, or so irregular as to resemble a jigsaw puzzle.

II.The folds appear as a series of light and dark lines, often temporal and confined to the posterior pole, rarely extending beyond the equator.

Fluorescein angiography shows a series of alternating hyperfluorescent (peaks of folds) and hypofluorescent (valleys of folds) streaks that start early in the arteriovenous (AV) phase, persist through the late venous phase, and do not leak. The hyperfluorescent areas may be the result of RPE thinning or atrophy. The hypofluorescent areas may be caused by an inclination of the RPE in the valleys, which results in increased RPE thickness blocking the choroidal fluorescence, or may be caused by a partial collapse of the choriocapillaris in the valleys. The folds may be bilateral.

III.Causes of choroidal folds include hypermetropia, macular degeneration, neural retinal detachment, hypotony, trauma, orbital tumors, thyroid disease, scleritis, uveitis, and others, including no known cause.

Choroidal folds are differentiated from neural retinal folds by the latter’s finer appearance and normal fluorescein pattern.

IV. Histologically, the choroid and Bruch’s membrane are corrugated or folded. RPE involvement seems to be a secondary phenomenon.

Heterochromia

See subsection Heterochromia Iridis and Iridum, this chapter, and p. 694 in Chapter 17.

Macular Degeneration

See p. 428 in Chapter 11.

DYSTROPHIES

Iris Nevus Syndrome

See p. 640 in Chapter 16.

Chandler’s Syndrome

See p. 640 in Chapter 16.

Essential Iris Atrophy

See p. 641 in Chapter 16.

Iridoschisis

See p. 641 in Chapter 16.

Choroidal Dystrophies

I.Regional choroidal dystrophies

A.Choriocapillaris atrophy involving the posterior eyegrounds

1.Involvement of the macula alone—also called central areolar choroidal sclerosis (Fig. 9.15), central progressive areolar choroidal dystrophy, and central choroidal angiosclerosis

a.The condition probably has an autosomal (recessive or dominant) inheritance pattern and is characterized by the onset of an exudative and edematous maculopathy in the third to the fifth decade.

Autosomal-dominant central areolar sclerosis is caused by an Arg-142-Trp mutation in the peripherin/RDS gene. Other mutations that code to the peripherin/ RDS gene include retinitis pigmentosa, macular dystrophy, pattern dystrophy, and fundus flavimaculatus.

b.Typical slow progression leads to a sharply demarcated, atrophic appearance involving only the posterior pole area, causing a central scotoma but no night blindness.