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

C

b.Five-year cumulative incidence rates in an older white population for preretinal macular fibrosis is 1.5% and for cellophane macula is 3.8%.

2.Most a ected patients have only mild visual disturbances.

a.Histologically, in both the idiopathic and the secondary varieties of epiretinal membranes, although there is an increased number of glial cells (fibrous astrocytes), with or without preservation of the normal neural retinal architecture, other cells such as RPE (often the predominant cell), fibrocytes, and myofibroblasts can be found. Depending on the composition of the membrane, immunohistochemical staining is positive for cytokeratin, glial fibrillary acidic protein, vimentin, actin, and fibronectin.

If the neural retina becomes atrophic and the normal retinal architecture becomes totally replaced by glial cells (e.g., in toxoplasmosis, where there may be complete replacement of a neural retinal segment by glial tissue), the neural retina becomes thinned. Conversely, with massive gliosis (see later) the neural retina becomes thickened.

II.Massive gliosis (Fig. 11.46; see also Fig. 18.11)

A.Criteria for massive gliosis are:

1.Segmental or total replacement of the neural retina by a mass of glial tissue

2.Abnormal blood vessels in the mass

3.A resultant thickening of the neural retina in the involved area

B.Massive gliosis is a benign, nonneoplastic proliferation of neural retinal glia either as an idiopathic, isolated finding or in response to diverse pathologic states initiated by a variety of factors (e.g., chronic inflammatory processes resulting in atrophia bulbi, congenital malformations, retinal vascular disorders, and trauma).

C.Histologically, the tumors are composed of: (1) interweaving groups of large, pale spindle cells that have rather uniform nuclei, abundant, faintly eosinophilic,

fibrillated cytoplasm, and indistinct cell borders; (2) dilated, large, abnormal blood vessels with thin walls and an anastomotic pattern; and (3) frequently calcium deposits in blood vessel walls and in the tumor.

1.Immunohistochemical staining is positive for S- 100 protein and glial fibrillary acidic protein.

2.Electron microscopy confirms the glial origin of the cells.

The proliferating cells are probably Müller cells. Rarely, massive gliosis can clinically mimic a choroidal malignant melanoma. Vasoproliferative retinal tumors (reactionary retinal glioangiosis; gliosis; see later) are most probably a form of massive gliosis.

3.True glioma—true gliomas of the neural retina are exceedingly rare and behave much like juvenile pilocytic astrocytomas of the optic nerve (see pp514–518 in Chapter 13).

Rarely, an oligodendroglioma can arise from retinal accessory glia.

III.Vasoproliferative retinal tumors (reactionary retinal glioangiosis)

A.Idiopathic

1.Usually solitary but may be multiple, di use, and even bilateral

2.Average age at onset 40 years, but with a range of

11 to 76 years

B.Secondary

1.Usually solitary or multiple, but may be di use and even bilateral

2.Secondary to such pre-existing entities as pars planitis, RP, and toxoplasmic retinitis

3.Average age at onset 36 years, but with a range of

2 to 75 years

C.Histology

1.Full-thickness neural retina is replaced by benign glial cell proliferation, vasoproliferation, and a sprinkling of round inflammatory cells (mainly lymphocytes).

2.The lesion is most probably a form of massive gliosis (see earlier).

Phakomatoses

See Chapter 2.

Retinal Pigment Epithelium

See Chapter 17.

Retinoblastoma and Pseudogliomas

See Chapter 18.

Neural Retinal Metastases (Fig. 11.47)

I.It seems paradoxical that choroidal metastases are common yet neural retinal metastases are rare.

II.Most neural retinal metastases are carcinomas (approximately half of these from lung), whereas the remainder are mainly metastases from cutaneous malignant melanomas.

Retinal metastasis (adenocarcinoma) has been reported in the Muir–Torre syndrome (sebaceous gland tumor and internal malignancy).

III.In the early stages, neural retinal metastasis may mimic an ischemic neural retinal infarction. As the tumor enlarges, it can simulate an inflammatory process.

IV. The histologic picture depends on the primary tumor.

NEURAL RETINAL DETACHMENT

Definitions

I.A neural retinal detachment is a separation between the neural retina and the RPE rather than a “true” neural retinal detachment (i.e., a separation of both neural retina and RPE from Bruch’s membrane).

II.An artifactitious neural retinal detachment (Fig. 11.48), a common finding after formaldehyde fixation, can be differentiated histologically from a true neural retinal detachment by the following:

A.An “empty” subneural retinal space

B.Good preservation of rods and cones

C.Pigment granules (derived from apices of RPE cells) adherent to the external ends of the rods and cones

Major Causes

I.Accumulation of fluid beneath an intact neural retina (e.g., in Harada’s disease, Coats’disease, malignant hypertension, eclampsia, choroidal malignant melanomas, or subneural

retinal hemorrhages)

II.Traction bands in the vitreous from many causes [e.g., vitreous bands in diabetes mellitus, posttraumatic vitreous condensation and fibrosis, and complications after cataract

extraction (especially with vitreous loss).]

III.Accumulation of fluid beneath a broken neural retina associated with vitreous traction (e.g., a rhegmatogenous neural retinal detachment)

Classification of Neural Retinal Detachment

I.Rhegmatogenous: caused by a neural retinal hole usually associated with vitreous traction

A.Equatorial type (mainly in age group older than 40 years): pathologic cause occurs at the equatorial area.

1.Myopia—approximately one-third of all nontraumatic neural retinal detachments occur in myopic patients, and approximately 1% to 3% of all patients who have high myopia experience a neural retinal detachment.

2.Secondary to lattice degeneration (see later)

3.Secondary to other perivascular degenerations

4.Secondary to neural retinal horseshoe tears (Fig. 11.49) or round holes (Fig. 11.50)

5.Secondary to uveitis—about 3% of patients who have uveitis will develop a rhegmatogenous retinal detachment

B.Oral type (mainly in age group older than 40 years, but somewhat younger than equatorial type): pathologic cause occurs at the ora serrata area.

1.Aphakic—before the era of extracapsular cataract extraction and lens implantation, approximately

20% of all neural retinal detachments occurred in aphakes, and a neural retinal detachment developed in approximately 2% to 5% of all aphakes.

Now, extracapsular cataract extraction is followed by neural retinal detachment in fewer than 1% of cases.

2.Dialysis in young—congenital and usually located inferotemporally

The congenital neural retinal disinsertion syndrome refers to cases of nonattachment of the neural retina with retinal dialysis (disinsertion).

3.Traumatic dialysis—usually superonasally

4.Giant neural retinal break (a neural retinal break greater than 90°)

C.Macular type (Fig. 11.51; rarest): pathologic cause occurs at the macula

1.High myopia

2.Posttraumatic

Causes of macular holes include trauma, cystoid macular edema, intraocular inflammation, vitreous traction, myopia, ARMD, and solar retinopathy. The pathogenesis of another cause, IMH, is not clear (see p. 437 in this chapter).

II.Nonrhegmatogenous: may be transudative, exudative, or hemorrhagic

A.Uveitis (e.g., pars planitis, sympathetic uveitis, Harada’s disease, posttraumatic, eclampsia, or Goodpasture’s syndrome)

Goodpasture’s syndrome is characterized by the onset of hemorrhagic pulmonary disease with glomerulonephritis, leading to progressive pulmonary and renal failure. The hallmark of the disease is linear deposition of antibasement membrane immunoglobulin G in the basement membranes of the kidneys, lungs, Bruch’s membrane, and choroidal vessels. Other ocular findings include choroidal infarction and macular edema.

B.Scleritis, especially posterior scleritis

C.Choroidal tumor: approximately 75% of uveal malignant melanomas have an associated neural retinal detachment, most of which (approximately 83%) are segmental.

D.Traction of vitreous bands [e.g., with retinopathy of prematurity, diabetic retinopathy (see Fig. 11.53C), sickle-cell retinopathy, or posttraumatic].

Predisposing Factors to Neural

Retinal Detachment

I. Juvenile and senile retinoschisis

II. Lattice (palisade) degeneration (Fig. 11.52)

A.Lattice degeneration may occur in any decade of life, with the average age between 40 and 50 years, a ects the sexes equally, is usually bilateral, and involves the neural retina circumferentially between the equator and the ora serrata.

In approximately 7% of cases, lattice degeneration occurs at an angle of 61° to 90° from the ora serrata, sometimes posterior to the equator, and often associated with a paraxial vessel. It is called radial perivascular lattice degeneration. An increased incidence of lattice degeneration is seen in patients who have retinopathy of prematurity.

B.Lattice degeneration consists of criss-crossing white lines (latticework) representing the branching pattern of thickened, hyalinized, retinal blood vessels. Pigmentation and depigmentation are common in the involved area, and the overlying vitreous is liquefied.

C.Vitreous condensations adhere to the edges or margins of the area of lattice; subsequent shrinkage or vitreous detachment may cause neural retinal tears.

D.In 20% to 30% of patients with neural retinal detachment, lattice degeneration is the cause; however, a neural retinal detachment develops in only approximately 1% of patients and 0.7% of eyes that have lattice degeneration.

Although approximately 99% of patients who have lattice degeneration never have a neural retinal detachment, an accompanying myopia exceeding 5 diopters puts these patients at a high risk for development of a detachment during their lifetime.

E.Histologically, the neural retina is thinned and gliosed

(especially the inner layers), and thick, hyalinized blood vessels are present.

1.No basement membrane (internal limiting membrane of the neural retina) exists over the area of lattice.

Vitreoretinal adhesions are mainly seen on the anterior side of the area of lattice degeneration.

2.The defect in the neural retinal basement membrane (internal limiting membrane) may be congenital and primary in causing lattice degeneration, or secondary to a tear or schisis in the adjacent vitreous body.

III.Retinal pits

A.Retinal pits, most often found in the peripheral neural retina, are small defects in the inner neural retinal layers.

B.They are probably caused by minute vitreoretinal adhesions adjacent to sclerotic blood vessels.

1.The adhesions may tear o a partial-thickness piece of neural retina at the time of a vitreous detachment.

2.Alternatively, the pit may be formed initially by focal atrophy of the Müller cells in the paravascular regions.

C.Histologically, a small, funnel-shaped defect occupies most of the thickness of the inner neural retina, often leaving only the receptors and the external part of the outer nuclear layer remaining.

IV. Vitreoretinal adhesions (see p. 483 in Chapter 12)

V.Trauma and cataract surgery (see p. 115–117 in Chapter 5)

Schwartz’s syndrome, which often follows trauma and is prevalent in male patients in their second or third decades, consists of rhegmatogenous neural retinal detachment, secondary aqueous cells (actually, not always cells, but photoreceptor outer segments), and increased intraocular pressure (instead of the usual decreased pressure associated with rhegmatogenous detachment).

VI. Myopia (see p. 423 in this chapter and p. 504 in Chapter 13)

VII. Paving stone degeneration (probably not a predisposing factor to neural retinal detachment; see p. 422 in this chapter)

Pathologic Changes After Neural

Retinal Detachment

I.Neural retinal atrophy (see Figs 11.48 and 11.53C)—the outer neural retinal layers are mainly a ected because they are removed from their source of nourishment (i.e., the choriocapillaris), whereas the inner neural retinal layers retain their blood supply from the central retinal artery.

Apoptosis is an important mechanism of photoreceptor cell degeneration in the early stage after traumatic neural retinal detachment.

II.The subneural retinal space is filled with material [e.g., serous fluid (see Fig. 11.48), blood, inflammatory cells, or neoplasm].

The material may be quite watery so that it runs out of the tissue during processing; the subneural retinal space then appears empty histologically.

III.Glial or RPE membranes can occur on the internal or external surface of the neural retina (Fig. 11.53) as well as in the neural retina (proliferative vitreoretinopathy—see p. 494 in Chapter 12). Shrinkage of these membranes causes fixed neural retinal folds (see Figs 11.45 and 11.53).

IV. RPE may proliferate at the anterior (usually ora serrata) or posterior edge of a detached neural retina.

A.The proliferated RPE at the posterior edge may lay

down considerable amounts of basement membrane* and is seen clinically and pathologically as a demarcation line (Fig. 11.54).

*Clinically, the basement membrane material should be clear or white. The proliferated RPE cells may accentuate the demarcation line by giving it a brown color.