hyperkeratosis

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hyperkeratosis

 [hi″per-ker″ah-to´sis]
1. hypertrophy of the horny layer of the skin, or any disease characterized by it.
2. hypertrophy of the cornea. adj., adj hyperkeratot´ic.
epidermolytic hyperkeratosis a hereditary autosomal dominant form of ichthyosis, present at birth. Characteristics include generalized redness of the skin and severe hyperkeratosis with small, hard wartlike scales over the entire body, accentuated in areas that flex or bend and sometimes involving the palms and soles. In infancy and childhood, there are recurrent bullae, most often on the lower limbs.
follicular hyperkeratosis a skin condition characterized by excessive development of keratin in hair follicles, resulting in rough, cone-shaped, elevated papules, the openings of which are often closed with a white plug of encrusted sebum. Deficiencies of vitamins A and E, B complex vitamins, and essential fatty acids have all been implicated in the etiology. Called also phrynoderma.
hyperkeratosis lenticula´ris per´stans an autosomal dominant skin disorder, usually occurring in the third or fourth decade of life, characterized by pink, red, or yellow to brown scaly papules on the lower leg and back of the foot, and sometimes on the trunk, thigh, arm, back and palm of the hand, or sole of the foot.

hy·per·ker·a·to·sis

(hī'pĕr-ker'ă-tō'sis),
Thickening of the horny layer of the epidermis or mucous membrane.
See also: keratoderma, keratosis.
Synonym(s): hyperkeratinization

hyperkeratosis

/hy·per·ker·a·to·sis/ (-ker″ah-to´sis)
1. hypertrophy of the stratum corneum of the skin, or any disease so characterized.
2. hypertrophy of the cornea.

epidermolytic hyperkeratosis  a hereditary disease, with hyperkeratosis, blisters, and erythema; at birth the skin is entirely covered with thick, horny, armorlike plates that are soon shed, leaving a raw surface on which scales then reform.
hyperkeratosis follicula´ris in cu´tem pe´netrans  Kyrle's disease.

hyperkeratosis

(hī′pər-kĕr′ə-tō′sĭs)
n. pl. hyperkerato·ses (-sēz)
Hypertrophy of the cornea or the horny layer of the skin.

hy′per·ker′a·tot′ic (-tŏt′ĭk) adj.

hyperkeratosis

[-ker′ətō′sis]
Etymology: Gk, hyper + keras, horn, osis, condition
overgrowth of the cornified epithelial layer of the skin. See also callus, corn. hyperkeratotic, adj.

hyperkeratosis

Dermatology An ↑ in superficial keratinized layers of certain epithelia, skin, and uterine cervix; hyperkeratosis usually represents a reaction to irritation, and generally overlies benign epithelium

hy·per·ker·a·to·sis

(hī'pĕr-ker'ă-tō'sis)
Thickening of the horny layer of the epidermis or mucous membrane.
See also: keratoderma, keratosis
Synonym(s): hyperkeratinization.

hyperkeratosis

Undue thickening of the outer layer of the skin so that a dense horny layer, such as a corn or callosity, results. This is a normal and essentially protective response to local pressure. Hyperkeratosis may also occur as an inherited disorder of the palms and the soles, or as ICHTHYOSIS.

hyperkeratosis

hypertrophy of stratum corneum in response to local mechanical trauma, e.g. intermittent pressure and/or friction (resulting in the formation of corn and/or callosity) or inherent skin pathology; presents as localized lesions (i.e. corns; see Table 1), generalized callosity, infection-associated keratoses (e.g. fungal infection) and diffuse hyperkeratosis in association with disease states (e.g. pachyderma congenita); prevention focuses on identification and resolution of the underlying cause, e.g. use of in-shoe orthoses and correct shoe fitting; treatment of pathological hyperkeratosis focuses on regular debridement/removal with a scalpel; ongoing management includes regular application of emollients, and, where appropriate, astringents or antifungal agents (see clavus; Table 2and Table 3)
Table 1: Types and presentations of corn (clavus)
Corn typeName (abbreviation)Typical siteLesion characteristics
HardHeloma durum (HD)Over bony prominences and jointsDark yellow; hard central nucleus, overlain by callosity
SoftHeloma molle (HM)At base of interdigital webspace/interdigital aspect of digit, overlying an interpahalangeal jointWhite/yellow macerated hyperkeratosis; shallow, rubbery nucleus
SeedHeloma miliare (HMill)Weight-bearing skin
Areas of dry skin
Isolated or groups of tiny hyperkeratotic lesions with very hard nuclei
FibrousAreas of skin under high load
Long-standing lesions
Long-term fibrosis ties lesion to underlying tissues; difficult to resolve fully
NeurovascularHeloma neurovasculare (HNV)Areas subject to high load and torsionAs HD, plus elements of vascular/nerve tissue within the nucleus; enucleation is usually painful
Durlacher'sLateral nail sulcus of varus fifth and fourth toesLocally painful; can be overlooked as they resemble nail tissue
SubungualSubungual heloma (HSub-ung)Nail bed, below the nail plate, or encroaching under the nail platePain; local dystrophy, onycholysis and yellow discoloration of overlying nail
Table 2: Types and presentations of corn (clavus)
Corn typeName (abbreviation)Typical siteLesion characteristics
HardHeloma durum (HD)Over bony prominences and jointsDark yellow; hard central nucleus, overlain by callosity
SoftHeloma molle (HM)At base of interdigital webspace/interdigital aspect of digit, overlying an interpahalangeal jointWhite/yellow macerated hyperkeratosis; shallow, rubbery nucleus
SeedHeloma miliare (HMill)Weight-bearing skin
Areas of dry skin
Isolated or groups of tiny hyperkeratotic lesions with very hard nuclei
FibrousAreas of skin under high load
Long-standing lesions
Long-term fibrosis ties lesion to underlying tissues; difficult to resolve fully
NeurovascularHeloma neurovasculare (HNV)Areas subject to high load and torsionAs HD, plus elements of vascular/nerve tissue within the nucleus; enucleation is usually painful
Durlacher'sLateral nail sulcus of varus fifth and fourth toesLocally painful; can be overlooked as they resemble nail tissue
SubungualSubungual heloma (HSub-ung)Nail bed, below the nail plate, or encroaching under the nail platePain; local dystrophy, onycholysis and yellow discoloration of overlying nail
Table 3: Treatment regimes for hyperkeratoses
Treatment regimeComments
Physical removalCareful scalpel debridement of callosity and corn enucleation, to return the skin to normal texture for the site; the prime approach to callous reduction
Topical medicamentsPyrogallol plaster 20-40%, applied for 3 days to neurovascular corns
Wheatgerm and pyrogallol (WP) ointment, applied to deep painful corns, after enucleation, for a maximum of three applications
Salicylic acid 12% in collodion, to assist softening and subsequent scalpel removal of heavy plantar callosity
Dichloroacetic acid, applied after scalpel debridement of heavy callosity, forming a rubbery coagulum, itself debrided away 14-21 days later
Potassium hydroxide 5% solution applied to callosity and left in situ for 7 days to macerate
Urea cream 10% applied liberally each night to hyperkeratosis and seed corns associated with atrophic dry skin, and the feet wrapped in cling film (Seran) until morning
Astringents for hyperhidrosis
Antifungals for athlete's foot
Emollients for anhidrosis
40% Silver nitrate or 60% ferric chloride solution to reduce hypertrophied dermal papillae
Aluminium acetate (Burow's) solution or kaolin powder mixed to a paste in water as a compress to areas of inflammation
Thermal techniquesCryosurgery
Electrosurgery and hyfrecation
Clinical padding See Table 4
OrthosesTemporary (chairside) or permanent simple insoles or casted orthoses
AdviceOn general foot care, suitable shoe styles and hosiery, home treatments for associated conditions (such as fungal infections, hyperhidrosis, anhidrosis, emollients, as appropriate), return period and treatment frequency

Note: The treatment of hyperkeratotic lesions must reflect the patient's overall condition (general health, drug therapy, occupation, activities, age, genetic make-up, skin type), the mechanical deformation of the skin during movement, against resistance, local friction, pressure and shear stresses, and the rate of desquamation from the stratum corneum.

Table 4: Examples of clinical pads
Pad typeExamplesDescription
Digital padsPlantar bar/long propSCF pad formed to infill the plantar aspect of the shanks of lesser toes, in order to prevent/reduce overcontraction of one or more lesser toes
Dorsal barSCF pad formed to infill the dorsal aspects of one or more hammered or retracted lesser toes, to reduce trauma to the skin overlying the prominent interphalangeal joints
Dorsoplantar splintSCF pad made as a combination of the plantar and dorsal bars, to correct digital deformity/reduce trauma to the apices and dorsa of lesser toes
Interdigital wedgeSCF or foam (plain, cavitied or holed) pad formed to match the dimensions of the interdigital space to reduce reformation of an interdigital heloma molle
Dorsal proximal/distal/apical/interdigital crescentA crescent-shaped pad applied proximal/distal to the dorsal/apical/interdigital area of a hyperkeratotic lesion on a digit, to reduce local pressure and friction
Dorsal horseshoeA horseshoe-shaped pad, where the 'arms' of the horseshoe cover the dorsal aspects of toes adjacent to the digit affected by a corn, and the U acts in the same manner as a crescent pad to protect the lesion
Plantar metatarsal padsPlantar coverA pad that covers the plantar skin of the forefoot, from the webbing to a line approximately 1cm distal to the bases of the metatarsals
U'd plantar coverA plantar cover into which a U has been cut to deflect pressure away from a plantar lesion. The U may be infilled with cushioning material
Winged plantar coverA plantar cover into which semicircular cutouts have been made, to deflect pressure from the 1 and/or 5 MTPJs
Plantar metatarsal padA pad applied to the 2/3/4 metatarsals, the distal limit of which applies pressure to the 2/3/4 metatarsal heads so that the 2/3/4 MTPJs are extended and the 2/3/4 toes realigned into a more functional position; the pad will also reduce compression between adjacent metatarsal heads
Plantar barA pad similar to a plantar cover, the distal limit of which had been shaped to accommodate up to 5 U'd areas
Shaft pad/long shaft padA pad applied to an individual metatarsal to allow sagittal-plane realignment
OthersD filler
Valgus pad
A pad that is shaped to infill the plantar aspect of the medial longitudinal arch to reduce excessive pronation or ease the pain of foot strain
Hallux valgus ovalAn oval pad, with or without a central cavity or hole, that is applied to the medial aspect of the 1 MTPJ to reduce local shear stresses in cases of HAV
Heel padA pad shaped to the plantar aspect of the heel, to cushion or reduce pressure to a plantar bursitis or heel spur
Posterior heel padA pad designed to deflect pressure from the posterior lateral area of the heel, in cases with Haglund's deformity
Doughnut pad
Ring pad
Oval pad
A circular pad with a central cavity or hole applied to the plantar aspect of the heel to protect the point of insertion of the plantar fascia
Cobra padA pad that combines a medial heel wedge, a valgus filler and a medial forefoot pad, to reduce excess foot pronation
Dumbbell padA pad that combines the action of a shaft pad to dorsiflex an individual metatarsal head, and an interdigital wedge, to reduce friction and pressure at the depth of the interdigital sulcus
Achilles tendon padA pad applied to the posterior aspect of the heel, to reduce pressure and friction at the insertion of the tendo Achilles

SCF, semicompressed felt; MTPJ, metatarsophalangeal joint; HAV, hallux abductovalgus.

hy·per·ker·a·to·sis

(hī'pĕr-ker'ă-tō'sis)
Thickening of the horny layer of the epidermis or mucous membrane.

hyperkeratosis

(hī´purker´ətō´sis),
n an excessive formation of keratin (e.g., as seen in leukoplakia).
Enlarge picture
Hyperkeratosis.
hyperkeratosis, benign,
n a nonmalignant form of a thickening condition that affects the keratin layer of the oral mucosa; generally appears as a white lesion.

hyperkeratosis

1. hypertrophy of the horny layer (stratum corneum) of the skin, or any disease characterized by it; the hyperkeratoses may have distinctive formats, e.g. annular (ring formations), basket-weave, compact, laminated.
2. hypertrophy of the cornea.

bovine hyperkeratosis
chlorinated naphthalene poisoning.
digital hyperkeratosis
increased thickness of the keratinized epidermis of footpads in dogs and rarely cats. May be in response to trauma or associated with distemper (hardpad disease), or pemphigus foliaceus.
epidermolytic hyperkeratosis
a form of ichthyosis in humans which is inherited as an autosomal dominant trait; there is severe degeneration of the granular layer of the epidermis.
juvenile hyperkeratosis
a crusting dermatosis over bony prominences, face and chin of young dogs. See zinc-responsive dermatosis.
nasal hyperkeratosis
an abnormal thickening, sometimes with fissures, of the planum nasale of dogs. May occur in association with digital hyperkeratosis (see above) as a feature of distemper (hardpad disease). Also seen in pemphigus foliaceus and discoid lupus erythematosus.
Enlarge picture
Nasal hyperkeratosis. By permission from Kummel BA, Color Atlas of Small Animal Dermatology, Mosby, 1989
nasodigital hyperkeratosis
see nasal hyperkeratosis, digital hyperkeratosis (above).
orthokeratotic hyperkeratosis
hyperkeratosis with non-nucleated cells present.
parakeratotic hyperkeratosis
hyperkeratosis with nucleated cells present; called also parakeratosis.
References in periodicals archive ?
Follicular hyperkeratosis with corkscrew hairs is present on skin examination in moderate to severe cases.
A patient may have night blindness, an eye disease called xerophthalmia that can lead to corneal ulcers and blindness, or a dry, scaly skin condition known as follicular hyperkeratosis.