Ординатура / Офтальмология / Английские материалы / Clinical Ophthalmology A Systematic Approach 7th Edition_Kanski, Bowling_2011

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Iris cysts

Primary

Primary iris cysts are rare lesions arising from the iris epithelium or, rarely, the stroma. Epithelial cysts lie between the two layers of the pigment epithelium (Fig. 12.17A).

1Epithelial

•Unilateral or bilateral, solitary or multiple globular structures which may be brown or transparent, depending on whether they arise in the iris epithelium or iridociliary epithelium respectively.

•Location may be at the pupillary border (Fig. 12.17B), in the midzone or the iris root.

•Occasionally they become dislodged and float freely in the anterior chamber (Fig. 12.17C) or vitreous.

•The vast majority are asymptomatic and innocuous. Rarely large cysts may obstruct vision and require treatment with argon laser photocoagulation.

2Stromal cysts present in the first years of life.

•Solitary and unilateral with a smooth translucent anterior wall.

•The cyst may remain dormant for many years or suddenly enlarge (Fig. 12.17D) and cause secondary glaucoma and corneal decompensation.

•Occasionally the cyst may break free from the iris and float in the anterior chamber or migrate to another location.

•Although spontaneous regression can occur, most require treatment by needle aspiration or surgical excision. Injection of ethanol into the cyst, removed after one minute, may avoid the need for excision of a recalcitrant cyst.

Fig. 12.17 Primary iris cysts. (A) Histology of epithelial cysts shows that they lie between the two layers of the pigment epithelium; (B) epithelial pupil margin cysts;

(C) dislodged epithelial cyst in the angle; (D) enlarging stromal cyst

(Courtesy of J Harry and G Misson, from Clinical Ophthalmic Pathology, Butterworth-Heinemann 2001 – fig. A; J McAllister – fig. D)

Secondary

Secondary iris cysts develop as a result of the following:

1Implantation cysts are the most common. They originate by deposition of surface epithelial cells from the conjunctiva or cornea on the iris after penetrating or surgical trauma.

aPearl cysts are white, solid lesions with opaque walls located in the stroma and are not connected to the wound (Fig.

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12.18A).

bSerous cysts are translucent, filled with fluid and may be connected to the wound (Fig. 12.18B). They frequently enlarge, leading to corneal oedema, anterior uveitis and glaucoma. Ultrasound biomicroscopy (UBM) may be used to delineate the extent of a lesion when surgical excision is contemplated.

2Prolonged use of long-acting miotics may be associated with usually bilateral small, multiple cysts located along the pupillary border (Fig. 12.18C). Their development can be prevented by the concomitant use of topical phenylephrine 2.5%.

3Parasitic cysts are very rare (Fig. 12.18D).

Fig. 12.18 Secondary iris cysts. (A) Pearl cyst; (B) large serous cyst following penetrating keratoplasty; (C) small pupil border cysts due to miotics; (D) parasitic cyst

(Courtesy of R Bates – fig. C)

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Ciliary body tumours

Ciliary body melanoma

Ciliary body melanomas comprise 12% of uveal melanomas.

Signs

1Presentation is usually in the 6th decade with visual symptoms although occasionally the tumour is discovered incidentally.

2Signs depend on the size and location of the tumour.

•The tumour may be visualized on fundoscopy following dilatation of the pupil (Fig. 12.19A).

•Dilated episcleral blood vessels in the same quadrant as the tumour (sentinel vessels – Fig. 12.19B).

•Erosion through the iris root that may mimic an iris melanoma (Fig. 12.19C).

•Pressure on the lens may give rise to astigmatism, subluxation or cataract formation (Fig. 12.19D).

•Extraocular extension through the scleral emissary vessels may produce a dark epibulbar mass (Fig. 12.19E) which may be mistaken for a conjunctival melanoma.

•Exudative retinal detachment may be caused by posterior extension (Fig. 12.19F).

•Anterior uveitis, caused by tumour necrosis, is uncommon.

•Circumferential (annular) growth for 360° carries the worst prognosis because early diagnosis is difficult.

Fig. 12.19 Ciliary body melanoma. (A) Tumour seen on fundoscopy; (B) ‘sentinel’ vessels in the same quadrant as the tumour; (C) erosion of the tumour through the iris root; (D) pressure on the lens; (E) extraocular extension; (F) displacement of the lens and inferior retinal detachment

(Courtesy of B Damato – fig. B; R Curtis – fig. D)

Investigations

1Three-mirror contact lens examination through a well-dilated pupil is essential and is particularly useful in detecting forward

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erosion through the iris root into the angle.

2UBM is very useful in showing the dimensions and extent of the tumour.

3Biopsy involving excisional, incisional or fine-needle aspiration techniques may be helpful in selected cases.

Treatment

1Iridocyclectomy for small or medium-sized tumours involving no more than one-third of the angle. Complications include vitreous haemorrhage, cataract, lens subluxation, hypotony and incomplete resection.

2Radiotherapy by brachytherapy or proton beam irradiation.

3Enucleation for large tumours and those causing secondary glaucoma, resulting from extensive invasion of Schlemm canal.

Differential diagnosis

1Uveal effusion syndrome may resemble circumferential ciliary body melanoma. However, the effusion is lobulated, transilluminates brightly and appears cystic on ultrasonography.

2Congenital epithelial iridociliary cysts may also displace the lens but can be readily differentiated from melanomas by ultrasonography.

3Other ciliary body tumours, which are extremely rare, include melanocytoma, medulloepithelioma, metastases, adenocarcinoma, adenoma neurolemmoma and leiomyoma. In most of these the correct diagnosis can be made only histologically.

Medulloepithelioma

Medulloepithelioma (previously known as diktyoma) is a rare embryonal neoplasm that arises from the inner layer of the optic cup and can be benign or malignant. The latter may be fatal as a result of intracranial spread or metastatic disease.

1Histology

•Teratoid tumours contain heterotopic elements or tissue such as brain, cartilage and skeletal muscle (Fig. 12.20A).

•Non-teratoid tumours lack these elements.

•Both types may be benign or malignant.

2Presentation is usually in the 1st decade with visual loss, pain, photophobia, leukocoria, or proptosis in advanced cases.

3Signs

•Unilateral white, pink, yellow or brown ciliary body mass that may be solid or polycystic (Fig. 12.20B).

•An anterior chamber mass that may contain grey-white opacities consisting of cartilage (Fig. 12.20C).

•A sheet-like tumour growing behind the lens may resemble a cyclitic membrane.

4 Complications include glaucoma, cataract and retinal detachment.

5 Treatment is difficult and most patients require enucleation.

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Fig. 12.20 Medulloepithelioma. (A) Histology of the teratoid type containing cartilage; (B) brown cystic ciliary body mass; (C) anterior segment mass

(Courtesy of J Harry – fig. A; R Curtis – fig. B)

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Tumours of the choroid

Choroidal naevus

Choroidal naevi are present in 5–10% of Caucasians but are very rare in dark-skinned races. They can be associated with NF1 and the dysplastic naevus syndrome. Although they are probably present at birth, growth occurs mainly during the pre-pubertal years and is extremely rare in adulthood. For this reason clinically detectable growth should arouse suspicion of malignancy.

Histology

The tumour is composed of a proliferation of spindle cell melanocytes (Fig. 12.21A).

Fig. 12.21 Choroidal naevus. (A) Histology shows proliferation of melanocytes in the choroid but sparing the choriocapillaris; (B) typical naevus; (C) naevus with surface drusen; (D) FA shows hypofluorescence of the naevus and hyperfluorescence of drusen; (E) ICGA shows hypofluorescence relative to the surrounding choroid; (F) B-scan shows slight elevation with high internal acoustic reflectivity

(Courtesy of J Harry – fig. A; M Karolczak-Kulesza – fig. F)

Signs

1Presentation. The vast majority of naevi are asymptomatic and detected by routine examination. Rarely symptoms may be caused by involvement of the fovea by the tumour itself or by serous retinal detachment.

2Signs of a typical naevus

•Usually post-equatorial, oval or circular, brown to slate-grey lesion with indistinct margins (Fig. 12.21B).

•Dimensions are <5 mm in basal diameter (i.e. 3 disc diameters) and <1 mm thickness.

•Surface drusen may be present, particularly in the central area of a larger lesion (Fig. 12.21C).

•Secondary choroidal neovascularization is uncommon.

•Typical naevi do not require follow-up because the risk of malignant transformation is extremely low.

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Investigations

1Photography as a baseline record is good practice.

2FA findings depend on the amount of pigmentation within the naevus and associated changes in the overlying RPE. Most naevi are avascular and pigmented, giving rise to hypofluorescence caused by blockage of background choroidal fluorescence. If the lesion is associated with surface drusen and RPE detachment, this will result in areas of hyperfluorescence (Fig. 12.21D). FA is not helpful in distinguishing a small melanoma from a naevus although multiple pinpoint areas of hyperfluorescence may predict future growth.

3ICGA shows hypofluorescence relative to the surrounding choroid (Fig. 12.21E).

4Ultrasonography (US) shows a localized flat or slightly elevated lesion with high internal acoustic reflectivity (Fig. 12.21F).

Atypical naevus

•An amelanotic naevus (Fig. 12.22A).

•A ‘halo’ naevus which is surrounded by a pale zone resembling choroidal atrophy (Fig. 12.22B).

Fig. 12.22 Unusual choroidal naevi. (A) Presumed amelanotic naevus; (B) ‘halo’ naevus

(Courtesy of B Damato – fig. A)

Suspicious naevus

1Clinical features. The following may suggest that a melanocytic lesion is not a naevus but a small melanoma.

•Documented growth.

•Symptoms such as blurred vision, metamorphopsia, field loss and photopsia.

•Dimensions >5 mm in diameter and >1 mm in thickness.

•Traces of surface orange pigment (lipofuscin).

•Absence of surface drusen on a thick lesion.

•Margin of the lesion at or near the optic disc.

•Serous retinal detachment either over the surface of the lesion or inferiorly.

The greater the number of these features, the higher the chance that the lesion is a melanoma.

2Management involves baseline fundus photography and ultrasonography, and then indefinite follow-up. If growth has been documented, the lesion should be reclassified as a melanoma and managed accordingly.

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Differential diagnosis

1 Congenital hypertrophy of the RPE is dark and flat, with a well defined outline.

2Melanocytoma of the choroid is clinically indistinguishable from a large naevus.

3Small melanoma is associated with serous retinal detachment and clumps of orange pigment.

Choroidal melanoma

Choroidal melanoma has an overall incidence of 5–7.5 per million per year in western hemisphere countries with no significant gender difference. It is the most common primary intraocular malignancy in adults and accounts for 80% of all uveal melanomas.

Pathology

1Cell type

aSpindle cells are arranged in tight bundles; their cell membranes are indistinct and the cytoplasm is fibrillary or finely granular. Nuclei vary from slender to plump and nucleoli may or may not be distinct (Fig. 12.23A).

bEpithelioid cells are larger and more pleomorphic than spindle cells, often appearing polyhedral with abundant eosinophilic cytoplasm. The cell membranes are distinct and an extracellular space often separates adjacent cells. The nuclei are large with a coarse chromatin pattern and prominent nucleoli. Mitotic figures are more frequent than in spindle cells (Fig. 12.23B).

2Classification of uveal melanomas.

a Spindle cell melanomas formed exclusively by spindle cells.

b Mixed cell melanomas in which there is a mixture of spindle and epithelioid cells.

3Other histological features

aFascicular pattern of cell growth which may be vasocentric in which the cells are arranged perpendicular to a central vessel (Fig. 12.23C), or ribbon-like.

b Necrosis where the cell type may not be recognizable (Fig. 12.23D).

4Pattern of tumour spread is as follows:

•Penetration of Bruch membrane and the RPE with herniation into the subretinal space, often with the development of a ‘collar-stud’ shape (Fig. 12.23E).

•Invasion of scleral channels for blood vessels and nerves resulting in orbital spread (Fig. 12.23F).

•Invasion of vortex veins.

•Metastatic haematogenous spread to the liver and occasionally to the lungs, bone, skin and brain.

•Optic nerve invasion is very rare, but may occur in eyes with large peripapillary melanomas.

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Fig. 12.23 Histology of choroidal melanoma. (A) Spindle cells – tightly arranged fusiformcells with indistinct cell membranes and slender or plump oval nuclei; (B) epithelioid cells – large pleomorphic cells with distinct cell membranes, large vesicular nuclei with prominent nucleoli, and abundant cytoplasm; (C) fascicular pattern – vasocentric; (D) necrotic tumour – cell type cannot be determined; (E) penetration of Bruch membrane in a ‘collar-stud’ fashion; (F) extraocular extension and an embolus of neoplastic cells within a blood vessel

(Courtesy of J Harry – figs A and B; J Harry and G Misson, from Clinical Ophthalmic Pathology, Butterworth-Heinemann 2001 – figs C, D, E and F)

Adverse prognostic factors

1Histological features implying an adverse prognosis include large numbers of epithelioid cells, long and wide nuclei, multiple nucleoli, closed vascular loops within the tumour and lymphocytic infiltration.

2Chromosomal abnormalities within the melanoma cells, particularly loss of chromosome 3 and gains in chromosome 8, are associated with a poor prognosis. Gains in the short arm of chromosome 6 carry a favourable prognosis.

3Size. Large tumours have a worse prognosis than small tumours because of lead time bias (i.e. the tumour and any metastases being present for a longer time), and because they tend to show aggressive histological and cytogenetic features.

4Extrascleral extension, because the tumour is more likely to be advanced and aggressive.

5Location. Anterior tumours involving ciliary body have a worse prognosis, most likely because they are relatively more advanced by the time of presentation.

6Local tumour recurrence after conservative treatment is associated with poor survival. This is probably because the recurrence is an indication that the original tumour was relatively aggressive.

Signs

1Presentation peaks at around the age of 60 years and occurs in one of the following ways.

•An asymptomatic tumour, usually in the periphery, is detected by chance on routine fundus examination performed for other reasons.

•A symptomatic tumour causes decreased visual acuity, blurring, metamorphopsia, visual field loss, floaters or photopsia.

2Signs

•A solitary elevated, subretinal, dome-shaped mass, which may be pigmented (Fig. 12.24A) or less commonly amelanotic (Fig. 12.24B); the former are usually grey or brown.

•About 60% of tumours are located within 3 mm of the optic disc or fovea.

•Clumps of orange pigment are frequently seen in the RPE overlying the tumour (Fig. 12.24C).

•If the tumour breaks through Bruch membrane it acquires a ‘collar-stud’ appearance, with visible blood vessels if the tumour is amelanotic (Fig. 12.24D).

•A diffuse tumour is rare and is characterized by an extensive flat or slightly raised morphology with grey or brown irregular

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discoloration (Fig. 12.24E).

•Exudative retinal detachment, initially confined to the surface of the tumour and which later shifts inferiorly and becomes bullous (Fig. 12.24F).

•Unlike rhegmatogenous retinal detachment, the subretinal fluid shifts with ocular movement and gravity (‘shifting fluid’). In addition, the retina does not show the fine, silvery rippling that occurs in the presence of a tear.

•Other signs include choroidal folds, intraocular inflammation, haemorrhage, rubeosis iridis, secondary glaucoma and cataract.

Fig. 12.24 Choroidal melanoma. (A) Highly pigmented melanoma; (B) amelanotic melanoma; (C) melanoma with surface orange pigment; (D) ‘collar-stud’ melanoma with intrinsic vessels; (E) diffuse melanoma; (F) large melanoma with subtotal retinal detachment

(Courtesy of B Damato – figs A, C and F); AD Singh, from Clinical Ophthalmic Pathology, Elsevier, 2007 – fig. E)

Special investigations

Although binocular indirect ophthalmoscopy combined with indirect slit-lamp biomicroscopy is sufficient for diagnosis in the vast majority of cases the following may be useful.

1FA is of limited diagnostic value because there is no pathognomonic pattern. The most common findings are intrinsic tumour (‘dual’) circulation (Fig. 12.25A), mottled fluorescence during the arteriovenous phase and late diffuse leakage and staining. FA may, however, be useful in the differential diagnosis of simulating lesions such as choroidal haemangiomas and haemorrhagic lesions.

2US is useful in detecting tumours when the media are opaque and to show extraocular extension. It is also useful in measuring tumour dimensions. The characteristic findings are internal homogeneity, choroidal excavation and orbital shadowing (Fig. 12.25B); a collar-stud configuration is almost pathognomonic (Fig. 12.25C).

3ICGA usually shows hypofluorescence throughout the study and provides more information than FA about the extent of the tumour, because there is less interference caused by RPE changes.

4MR shows hyperintensity in T1-weighted images (Fig. 12.25D) and hypointensity in T2-weighted images, but these features are not pathognomonic. Enhancement with gadolinium improves image quality, demonstrating optic nerve and orbital invasion and facilitating differentiation from other tumours.

5 Colour-coded Doppler imaging may differentiate pigmented tumours from haemorrhage, particularly in eyes with opaque media.

6Biopsy is useful when the diagnosis cannot be established by less invasive methods. It may be performed either with a fine needle or using the 25-gauge vitrectomy system, the latter providing a larger sample.

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