Skin and Lacrimal Drainage System

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6

Skin and Lacrimal Drainage System

Skin

Normal Anatomy (Figs. 6.1 and 6.2)

Epidermis

Lid skin is quite thin.

Dermis

The dermis is sparse, composed of delicate collagen fibrils, and contains the vasculature and epidermal appendages, sebaceous glands, apocrine and eccrine sweat glands, and hair complexes.

Subcutaneous Tissue

The subcutaneous layer is mostly composed of adipose tissue.

Terminology

Orthokeratosis and Parakeratosis

I. The stratum corneum (keratin layer) is thickened.

Hyperkeratosis means “increased scale” and includes both orthokeratosis and parakeratosis. In orthokeratosis, a thick granular layer is found because the epidermal cells slowly migrate upward; when the migration upward is rapid, no granular cells are seen and parakeratosis results. Orthokeratosis is hyperkeratosis composed of cells that have complete keratinization and no nuclear remnants, whereas parakeratosis is hyperkeratosis that shows incomplete keratinization in which nuclei are retained in the cells of the stratum corneum. Orthokeratosis and parakeratosis often exist in the same lesion (Fig. 6.3A).

II. Orthokeratosis commonly is seen in verruca and the scaly lesions such as actinic and seborrheic keratoses.

III. Parakeratosis is characteristic of psoriasis and other inflammatory conditions (e.g., seborrheic keratosis).

Bulla

I. A bulla is a fluid-filled space in or beneath the epidermis (see Fig. 6.5).

Spongiosis is fluid accumulation between keratinocytes (intercellular edema), which may lead to cleft or vesicle formation. It is commonly seen in inflammatory conditions, especially the spectrum of dermatitides. Ballooning is intracellular edema characteristic of virally infected cells.

II. A small bulla is arbitrarily called a vesicle.

Vesicles and bullae may arise from primary cell damage or acantholysis. They may be located under the keratin layer (subcorneal), between the epithelium and dermis (junctional), or in the middle layers of epithelium.

Atrophy

I. Atrophy (see subsection Atrophy later, under Aging, and Fig. 6.8) is (1) thinning of the epidermis; (2) smoothing or diminution (effacement) of rete ridges (“pegs”); (3) disorder of epidermal architecture; (4) diminution or loss of epidermal appendages such as hair; and (5) alterations of the collagen and elastic dermal fibers.

II. Atrophy is commonly seen in aging. It may also be seen in the epidermis overlying a slow-growing tumor in the corium.

Atypical Cell

I. An atypical cell (see Fig. 6.4B) is one in which the normal nucleus-to-cytoplasm ratio is altered in favor of the nucleus, which stains darker than normal (hyperchromasia), may show an abnormal configuration (giant form or multinucleated form), may have an abnormal nuclear configuration (e.g., indented, cerebriform, multinucleated), or may contain an abnormal mitotic figure (e.g., tripolar metaphase). If sufficiently atypical, according to generally accepted criteria, the cell may be classified as cancerous.

It is the overall pattern of the tissue rather than any one individual cell that aids in the diagnosis of cancer; one dyskeratotic or atypical cell does not necessarily mean the tissue is cancerous.

II. Isolated atypical cells may be found in benign conditions such as actinic keratosis and pseudoepitheliomatous hyperplasia. Atypical cells may be abundant in malignant conditions such as carcinoma in situ and squamous cell carcinoma.

Congenital Abnormalities

Dermoid and Epidermoid Cysts

See Chapter 14.

Phakomatous Choristoma

I. Phakomatous choristoma (Fig. 6.6) is a rare, congenital, choristomatous tumor (i.e., a tumor of tissue not normally found in the area) of lenticular anlage, usually involving the inner aspect of the lower lid.

II. Histologically, cells resembling lens epithelial cells and lens “bladder” cells along with patches of a thick, irregular periodic acid–Schiff (PAS)-positive membrane closely simulating lens capsule are seen growing irregularly in a dense fibrous tissue matrix.

Positive staining for vimentin, S-100 protein, and numerous antibodies against lens-specific proteins strongly supports the lenticular anlage origin.

Positive staining for vimentin, S-100 protein, and numerous antibodies against lens-specific proteins strongly support the lenticular anlage origin. An unusual complex choristoma of the lateral canthus has been reported to contain elements of hair follicle nevus, bulbar dermoid, epibulbar osseous choristoma, and accessory tragus.

Miscellaneous Choristomas and Hamartomas

I. Nevus lipomatosus (pedunculated nevus) is a gradually enlarging congenital eyelid papule. Histologically, the lesion is polypoid in shape and consists of mature adipocytes within the dermis and subconjunctival mucosa consistent with nevus lipomatosus.

II. Juvenile hyaline fibromatosis is characterized by multiple facial nodules, gingival fibromatosis, and osteolytic lesions in the proximal metaphysis of the tibia and humerus symmetrically. It may present as an eyelid tumor scalloping the superior orbital osseous rim and resulting in blepharoptosis.

III. Neurocutaneous pattern syndromes are a group of disorders characterized by congenital abnormalities involving both the skin and the nervous system for which no identifiable cause has been isolated. Examples are encephalocraniocutaneous lipomatosis, oculocerebrocutaneous syndrome, and linear nevus sebaceous syndrome.

A. Encephalocraniocutaneous lipomatosis is rare and characterized by congenital cutaneous, ocular, and neurologic abnormalities, particularly involving the head and neck.

It has been reported in a boy with lipomatous brown pigmented plaques of the top of the skull with accompanying alopecia, ptosis, bulbar conjunctival lipodermoid, microcalcifications, and atrophy of the cerebral parenchyma, and widening of the frontal subarachnoid space and the fissure of Sylvius. There were accompanying intraoral lesions, maxillary compound odontoma, and juvenile extranasopharyngeal angiofibroma of the gingiva.

B. Congenital lipoblastoma of the scalp and eyelid is very rare. Histopathologic examination shows lobular adipose tissue separated by fibrous septa.

IV. Caliber persistent artery refers to a large-caliber artery that is present adjacent to an epithelial or mucosal surface.

A. On the head and neck, the lesion most commonly is found on the lower lip, but it has been documented on the eyelid.

B. It is of significance because of the possibility of confusion with a subcutaneous mass lesion and because of its propensity to bleed profusely on attempted biopsy.

C. Histopathologic examination demonstrates a large-caliber artery within the dermis extending at almost right angles to the skin surface.

Cryptophthalmos (Ablepharon)

Microblepharon

Microblepharon is a rare condition in which the lids are usually normally formed but shortened; the shortening results in incomplete lid closure.

Coloboma

I. A coloboma of the lid is a defect that ranges from simple notching at the lid margin to complete absence of a segment of lid.

II. Other ocular and systemic anomalies may be found (see discussion of Goldenhar’s syndrome in Chapter 8).

Eyelid colobomas may be seen in the amniotic deformity, adhesion, and mutilation (ADAM) sequence in which a broad spectrum of anomalies having intrinsic causes (germ plasm defect, vascular disruption, and disturbance of threshold boundaries of morphogens during early gastrulation) alternate with extrinsic causes (amniotic band rupture) to explain the condition. In addition to mutilation (reduction) and deformity (ring constriction) of distal extremities, there can be acrania, cephalocele, typical or atypical facial clefts, and celosomia in addition to skin evidence of a constriction band.

Ectopic Caruncle

A clinically and histologically normal caruncle may be present in the tarsal area of the lower lid.

Eyelash Anomalies

I. Hypotrichosis (madarosis)

A. Primary hypotrichosis (underdevelopment of the lashes) is rare.

Schopf–Schulz–Passarage syndrome is a rare ectodermal dysplasia characterized by hypodontia, hypotrichosis, nail dystrophy, palmoplantar keratoderma, and periocular and eyelid margin hidrocystomas. Multiple palmoplantar eccrine syringofibroadenomas have also been associated with the syndrome.

B. Most cases are secondary to chronic blepharitis or any condition that causes lid margin scarring or lid neoplasms—for example, sebaceous gland carcinoma.

C. Secondary eyelash loss may be associated with hyperthyroidism.

II. Hypertrichosis is an increase in length or number of lashes.

A. Trichomegaly is an increase in the length of the lashes.

Increased eyelash length may be associated with allergic diseases.

B. Polytrichia is an increase in the number of lashes: (1) distichiasis—two rows of cilia; (2) tristichiasis—three rows of cilia; and (3) tetrastichiasis—four rows of cilia.

Distichiasis is the term used for the congenital presence of an extra row of lashes, whereas trichiasis is the term used for the acquired condition, which is usually secondary to lid scarring. Distichiasis may be associated with late-onset hereditary lymphedema (see section on Congenital Conjunctival Lymphedema in Chapter 7). The syndrome is characterized by lymphedema of the limbs, with variable age of onset, and extra aberrant growth of eyelashes from the meibomian glands. Mutation of the FOXC2 gene (a member of the forkhead/winged family of transcription factors) has been associated with the lymphedema–distichiasis syndrome. It has been postulated that hereditary distichiasis and lymphedema–distichiasis may not be separate genetic disorders but, rather, different phenotypic expressions of the same underlying disorder. Continue small print. A form of congenital hypertrichosis in the periorbital region, associated with cutaneous hyperpigmentation, may overlie a neurofibroma.

III. Ectopic cilia

A. Ectopic cilia is a rare choristomatous anomaly in which a cluster of lashes grows in a location (lid or conjunctiva) remote from the eyelid margin.

B. A case of complex eyelid choristoma containing ectopic cilia and a functioning lacrimal gland has been reported.

Ichthyosis Congenita

I. Ichthyosis (Fig. 6.7) can be divided into four types:

A. Autosomal-dominant ichthyosis vulgaris (onset usually in first year of life)

B. Autosomal-dominant ichthyosis congenita (ichthyosiform erythroderma, onset at birth), with a generalized bullous form and a localized nonbullous form (ichthyosis hystrix)

C. X-linked recessive ichthyosis vulgaris [the rarest type (Xp22.32), onset at 1–3 weeks]

D. Autosomal-recessive ichthyosis congenita with a severe harlequin type and a less severe lamellar type (onset at birth)

1. Keratinocyte transglutaminase (TGK) activity mediates the cross-linkage during the formation of the normal cornified cell membrane.

2. Intact cross-linkage of cornified cell envelopes is required for epidermal tissue homeostasis.

3. In lamellar ichthyosis, TGK levels are drastically reduced, causing the keratinocytic defect in the disease.

II. All types have in common dryness of the skin with variable amounts of profuse scaling.

Only in the autosomal-recessive type do ectropion of the lids and conjunctival changes develop.

III. Cicatricial ectropion is a common finding in recessive ichthyosis congenita.

A. Corneal changes such as gray stromal opacities (dystrophica punctiformis profunda) occur in ichthyosis vulgaris and autosomal-recessive ichthyosis congenita.

In X-linked ichthyosis, corneal changes may occur that electron microscopically resemble the changes in lecithin cholesterol acyltransferase disease.

B. Superficial corneal changes (punctate epithelial erosions, gray elevated nodules, and band-shaped keratopathy) also occur.

IV. The differential diagnosis includes ectodermal dysplasia, poikiloderma congenitale (Rothmund–Thomson syndrome), adult progeria (Werner’s syndrome), keratosis palmaris et plantaris, keratosis follicularis spinulosa decalvans (Siemens’ disease), epidermolysis bullosa, and the syndrome of ichthyosis follicularis, atrichia, and photophobia (IFAP syndrome, a rare neuroichthyosis that is probably X-linked recessive).

Keratitis–ichthyosis–deafness (KID) syndrome is a rare congenital ectodermal dysplasia characterized by the presence of hyperkeratotic skin lesions, moderate to profound sensorineural hearing loss, and vascularizing keratitis. Genetic mutations in the GJB2 gene coding for connexin 26, which is a component of gap junctions in epithelial cells, have been detected in the disorder. Specific associated ocular and adnexal findings are lid abnormalities, corneal surface instability, limbal stem cell deficiency with resulting corneal complications, and dry eye.

V. Histologically, the epidermis is thickened and covered by a thick, dense, orthokeratotic scale.

In the autosomal-recessive type, the conjunctiva may show a papillary reaction with hyperkeratosis and parakeratosis of the epithelium.