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

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Fig. 1.28 Merkel cell carcinoma. (A) Histology shows a sheet of Merkel cells; (B) clinical appearance

(Courtesy of J Harry and L Misson, from Ocular Ophthalmic Pathology, Butterworth-Heinemann 2001 – fig. A)

Kaposi sarcoma

Kaposi sarcoma is a vascular tumour which typically affects patients with the acquired immune deficiency syndrome (AIDS). Many patients have advanced systemic disease although in some instances the tumour may be the only clinical manifestation of HIV infection.

1 Histology shows proliferating spindle cells, vascular channels and inflammatory cells within the dermis (Fig. 1.29A). 2 Signs. A pink, red-violet to brown lesion (Fig. 1.29B) which may be mistaken for a haematoma or a naevus.

3Treatment is by radiotherapy or excision.

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Fig. 1.29 Kaposi sarcoma. (A) Histology shows a proliferation of predominantly spindle-shaped cells; vascular channels are evident; (B) clinical appearance

(Courtesy of J Harry – fig. A)

Treatment of malignant tumours

Biopsy

The two types of biopsy are (a) incisional, using a blade or a biopsy punch, in which only part of the lesion is removed to allow histological diagnosis, and (b) excisional, in which the entire lesion is removed and a histological diagnosis made; the latter may be:

1 Shave excision using a blade to remove shallow epithelial tumours, such as papillomas and seborrhoeic keratosis.

2Full-thickness skin excision for tumours that are not confined to the epidermis.

Surgical excision

Surgical excision aims to remove the entire tumour with preservation of as much normal tissue as possible. Smaller tumours can be removed via an excision biopsy and the defect closed directly, whilst awaiting histological confirmation of complete clearance. Most small BCCs can be cured by excision of the tumour together with a 2–4 mm margin of clinically normal tissue. More radical surgical excision is required for large BCC and aggressive tumours such as SCC, SGC and melanoma. It may not be possible to close the defect at the time of initial removal, but it is necessary to ensure complete clearance of tumour prior to undertaking any reconstruction. Rapid processing of paraffin-embedded specimens can reduce the interval to confirmation of histological clearance but still requires closure as a separate procedure. Faster confirmation can be achieved using either frozen-section control or micrographic surgery, and reconstruction can then take place on the same day.

1Standard frozen section involves histological examination of the margins of the excised specimen at the time of surgery to ensure that they are tumour-free. If no tumour cells are detected, the eyelid is reconstructed; if some are present in a particular area, further excision is performed until the specimen is tumour-free.

2Mohs micrographic surgery involves layered excision of the tumour. Specimens around the eye are usually examined frozen as the fixing paste used in the technique as initially described produces ocular irritation. Processing of each layer enables a map of the edges of the tumour to be developed. Further tissue is taken in any area where tumour is still present until clearance is achieved. Although time-consuming, this technique maximizes the chances of total tumour excision whilst minimizing sacrifice of normal tissue. This is a particularly useful technique for tumours that grow diffusely and have indefinite margins with finger-like extensions, such as sclerosing BCC, SCC, recurrent tumours and those involving the medial or lateral canthi. However, the irregular contours around the eyelids and extension of tumours into orbital fat can make interpretation difficult, and specialist training is required in this technique.

Reconstruction

The technique of reconstruction depends on the extent of tissue removed and whether this is fullor partial-thickness. It is important to

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reconstruct both anterior and posterior lamellae. If one of the lamellae has been sacrificed during excision of the tumour, it must be reconstructed with similar tissue. Anterior lamellar defects may be closed directly or with a local flap or skin graft. Full-thickness defects may be repaired as follows:

1Small defects involving less than one-third of the eyelid can usually be closed directly, provided the surrounding tissue is sufficiently elastic to allow approximation of the cut edges (Fig. 1.30). If necessary, a lateral cantholysis can be fashioned to mobilize additional tissue if the defect cannot be reapproximated.

2 Moderate size defects involving up to half of the eyelid may require a flap (e.g. Tenzel semicircular) for closure (Fig. 1.31).

3Large defects involving over half of the eyelid may be closed by one of the following techniques:

aPosterior lamellar reconstruction may involve an upper lid free tarsal graft, buccal mucous membrane or hard palate graft, or a Hughes flap from the upper lid (Fig. 1.32).

bAnterior lamellar reconstruction may involve skin advancement, a local skin flap or a free skin graft (Fig. 1.33). At least one reconstructed lamella requires its own blood supply to maximize the viability of any free graft.

Fig. 1.30 Direct closure. (A) Pre-operative appearance of a basal cell carcinoma; (B) appearance following excision; (C) direct closure of defect

(Courtesy of A Pearson)

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Fig. 1.31 Tenzel flap. (A) Pre-operative appearance; (B) appearance following excision; (C) appearance following closure of the flap

(Courtesy of A Pearson)

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Fig. 1.32 Posterior lamellar reconstruction with a Hughes upper lid flap. (A) Preoperative appearance; (B) appearance following excision; (C) postoperative appearance with the flap yet to be divided

(Courtesy of A Pearson)

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Fig. 1.33 Anterior lamellar reconstruction with a free skin graft. (A) Pre-operative appearance; (B) appearance following excision; (C) skin graft in place

(Courtesy of A Pearson)

Laissez-faire

Full reconstruction of the defect created by tumour removal may not always be required. In the laissez-faire approach the wound edges are approximated as far as possible and the defect is allowed to granulate and heal by secondary intention. Even large defects can often achieve a satisfactory outcome with time.

Radiotherapy

The recurrence rate following irradiation is higher than after surgery, and radiotherapy does not allow histological confirmation of tumour eradication. Recurrences following radiotherapy are difficult to treat surgically because of the poor healing properties of irradiated tissue.

1Indications

•Small BCC which does not involve the medial canthal area in patients who are either unsuitable for or refuse surgery.

•Highly radiosensitive tumours such as Kaposi sarcoma.

2Contraindications

•Medial canthal BCC because radiotherapy would damage the canaliculi and result in epiphora.

•Upper eyelid tumours because subsequent keratinization results in a chronically uncomfortable eye.

•Aggressive tumours such as sclerosing BCC, SCC and SGC.

3Complications

•Skin damage and madarosis.

•Nasolacrimal duct stenosis following irradiation to the medial canthal area.

•Conjunctival keratinization, dry eye, keratopathy and cataract.

•Retinopathy and optic neuropathy.

Many of these complications can be avoided if the globe is protected by a special shield during irradiation.

Cryotherapy

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1Indications. May be considered for small superficial BCC.

2Contraindications are similar to those of radiotherapy, although cryotherapy may be a useful adjunct to surgery in patients with epibulbar pagetoid extensions of SGC, sparing the patient an extenteration.

3Complications include skin depigmentation, madarosis and conjunctival overgrowth.

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Disorders of lashes

Anatomy

The lashes (cilia) are slightly more numerous in the upper (approximately 100) than in the lower lid. The lash roots lie against the anterior surface of the tarsus. The cilia pass between the orbicularis oculi and the muscle of Riolan, exiting the skin at the anterior lid margin and curve away from the globe. Scarring of the tarsal plate and conjunctiva can alter their position and direction. Following intense inflammation lashes may grow abnormally from meibomian gland openings (distichiasis).

Trichiasis

Trichiasis is a very common acquired condition which may occur in isolation or as a result of scarring of the lid margin secondary to chronic blepharitis and herpes zoster ophthalmicus. Trichiasis should not be mistaken for pseudotrichiasis secondary to entropion when in some cases the in-turning of the eyelid may be intermittent and the condition may be mistaken for true trichiasis and inappropriately treated.

Signs

Trichiasis is characterized by posterior misdirection of lashes arising from normal sites of origin (Fig. 1.34A and B). Trauma to the corneal epithelium may cause punctate epithelial erosions, with ocular irritation worsened by blinking. Corneal ulceration and pannus formation may occur in severe long-standing cases.

Fig. 1.34 Trichiasis. (A) Mild; (B) severe; (C) cryotherapy; (D) appearance following laser ablation

(Courtesy of A Pearson – figs A and C)

Treatment

1Epilation with forceps is simple and effective but recurrences within 4–6 weeks are almost inevitable.

2Electrolysis is useful for a few isolated lashes but is tedious and may cause scarring. Frequently multiple treatments are required to obtain a satisfactory result. An electrocautery needle is inserted down the shaft of the lash root and current applied until coagulated tissue bubbles to the surface. The lash is then removed. Retreatment for recurrences is required in about 40% of cases.

3Cryotherapy is very effective in eliminating profuse lashes (Fig. 1.34C). With a special cryoprobe a double freeze–thaw cycle at −20°C is applied. Complications include necrosis, depigmentation (especially in dark-skinned individuals), damage to meibomian glands which may adversely affect the precorneal tear film, and notching of the lid margin.

4 Argon laser ablation is useful for a few scattered lashes and is performed as follows:

aThe initial settings are 50 µm, 0.2 second and 1000 mW.

bThe laser is fired at the root of the lash and a small crater formed.

cThe spot size is increased to 200 µm and the crater deepened to reach the follicle (Fig. 1.34D).

d Most patients are cured by one or two sessions.

5Surgery involving full-thickness wedge resection or anterior lamellar rotation excision may be useful for a localized crop of lashes

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resistant to other methods of treatment.

Congenital distichiasis

Congenital distichiasis is a rare condition that occurs when a primary epithelial germ cell destined to differentiate into a specialized sebaceous gland (meibomian gland) of the tarsus develops into a complete pilosebaceous unit. The condition is frequently inherited in an AD manner with high penetrance but variable expressivity. The majority of patients also manifest primary lymphoedema of the legs (lymphoedema–distichiasis syndrome).

1Signs

•A partial or complete second row of lashes emerging at or slightly behind the meibomian gland orifices.

•The aberrant lashes tend to be thinner and shorter than normal cilia and are often directed posteriorly. They are usually well tolerated during infancy and may not become symptomatic until the age of 5 years.

2Treatment of the lower lid is with cryotherapy. Distichiasis of the upper lid involves lamellar eyelid division and cryotherapy, which is performed as follows:

a An incision is made along the grey line dividing the lid into anterior and posterior lamellae (Fig. 1.35A).

bThe posterior lamella and lash follicles are frozen to −20°C with a double freeze–thaw cycle (Fig. 1.35B).

cThe lamellae are surgically re-apposed.

Fig. 1.35 (A) Lamellar lid separation; (B) cryotherapy to the posterior lamella

(Courtesy of AG Tyers and JRO Collin, from Colour Atlas of Ophthalmic Plastic Surgery, Butterworth-Heinemann 2001)

Acquired distichiasis

Acquired distichiasis (metaplastic lashes) is caused by metaplasia and dedifferentiation of the meibomian glands to become hair follicles. The most important cause is late stage cicatrizing conjunctivitis associated with chemical injury, Stevens–Johnson syndrome and ocular cicatricial pemphigoid.

1Signs

•Variable number of lashes which originate from meibomian gland orifices.

•Unlike congenital distichiasis, the cilia tend to be non-pigmented and stunted (Fig. 1.36), and are usually symptomatic.

2Treatment of mild cases is as for trichiasis. Severe cases require lamellar eyelid division and cryotherapy to the posterior lamella.

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Fig. 1.36 Acquired distichiasis

(Courtesy of R Bates)

Eyelash ptosis

Eyelash ptosis is a downward sagging of upper eyelid lashes (Fig. 1.37A). The condition may be idiopathic or associated with floppy eyelid syndrome, dermatochalasis with anterior lamellar slip or long-standing facial palsy.

Fig. 1.37 Miscellaneous eyelash disorders. (A) Eyelash ptosis; (B) trichomegaly; (C) madarosis; (D) poliosis

(Courtesy of A Pearson – fig. A; L Merin – fig. B; S Tuft – fig. C)

Trichomegaly

Trichomegaly is excessive eyelash growth (Fig. 1.37B); the main causes are listed in Table 1.1.

Table 1.1 -- Causes of trichomegaly

1Acquired

•Drug-induced – topical prostaglandin analogues phenytoin and ciclosporin

•Malnutrition

•AIDS

•Porphyria

•Hypothyroidism

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