Medical Dictionary

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keratinophilic (ke-rat′i-no-fil′ik)
Denoting fungi that use keratin as a substrata, e.g., dermatophytes. [keratin + Gr. philos, love, attraction, + -ic]

keratinosome (ke-rat′i-no-som)
A membrane-bound granule, 100 to 500 nm in diameter, located in the upper layers of the stratum spinosum of certain stratified squamous epithelia. SYN: lamellar granule, membrane-coating granule, Odland body.

keratinous (ke-rat′i-nus)
1. Relating to keratin. 2. SYN: horny.

keratitis (ker-a-ti′tis)
Inflammation of the cornea. SEE ALSO: keratopathy. [kerato- + G. -itis, inflammation] actinic k. a reaction of the cornea to ultraviolet light. deep punctate k. sharply defined opacities in an otherwise clear cornea, occurring in syphilitic iritis. dendriform k., dendritic k. a form of herpetic k.. diffuse deep k. SYN: k. profunda. Dimmer k. SYN: k. nummularis. disciform k. large disk-shaped infiltration of the central or paracentral corneal stroma. This lesion is deep and nonsuppurative and is seen in virus infections, particularly herpetic. SYN: k. disciformis. k. disciformis SYN: disciform k.. exposure k. inflammation of the cornea resulting from irritation caused by inability to close the eyelids. SYN: lagophthalmic k.. fascicular k. a phlyctenular k. followed by the formation of a band or fascicle of blood vessels extending from the margin toward the center. filamentary k. a condition characterized by the formation of epithelial filaments of varying size and length on the corneal surface. SYN: k. filamentosa. k. filamentosa SYN: filamentary k.. geographic k. k. with coalescence of superficial lesions in herpes k.. herpetic k. inflammation of the cornea (or cornea and conjunctiva) due to herpes simplex virus. SYN: herpes corneae, herpetic keratoconjunctivitis. interstitial k. an inflammation of the corneal stroma, often with neovascularization. lagophthalmic k. SYN: exposure k.. k. linearis migrans a deep, linear corneal opacity stretching from limbus to limbus; associated with congenital syphilis. marginal k. a corneal inflammation at the limbus. metaherpetic k. a postinfectious corneal inflammation in herpetic k. leading to epithelial erosion; not due to virus replication. mycotic k. an infection of the cornea of the eye caused by a fungus. necrotizing k. severe inflammation and destruction of corneal tissue that may be seen in response to herpes infection. neuroparalytic k. SYN: neurotrophic k.. neurotrophic k. inflammation of the cornea after corneal anesthesia. SYN: neuroparalytic k.. k. nummularis coin-shaped or round, discrete, grayish areas 0.5 to 1.5 mm in diameter scattered throughout the various layers of the cornea. SYN: Dimmer k.. phlyctenular k. an inflammation of the corneal conjunctiva with the formation of small red nodules of lymphoid tissue (phlyctenulae) near the corneoscleral limbus. SYN: scrofulous k.. pneumococcal/suppurative k. SYN: serpiginous k.. polymorphic superficial k. epithelial degeneration occurring in starvation. k. profunda an inflammation of the posterior corneal stroma. SYN: diffuse deep k.. punctate k., k. punctata SYN: keratic precipitates, under precipitate. sclerosing k. inflammation of the cornea complicating scleritis; characterized by opacification of the corneal stroma. scrofulous k. SYN: phlyctenular k.. serpiginous k. a severe, creeping, central, suppurative ulcer often due to pneumococci. SYN: pneumococcal/suppurative k., serpent ulcer of cornea. k. sicca SYN: keratoconjunctivitis sicca. superficial linear k. spontaneous, painful k. with epithelial erosion and folds in Bowman membrane. superficial punctate k. epithelial punctate k. associated with viral conjunctivitis. SYN: Thygeson disease. trachomatous k. pannus, corneal pannus. vascular k. superficial cellular infiltration of the cornea and neovascularization between Bowman membrane and the epithelium. vesicular k. k. with coalescence of areas of epithelial corneal edema. xerotic k. SYN: keratomalacia.

kerato-, kerat-
1. The cornea. 2. Horny tissue or cells. SEE ALSO: cerat-, cerato-. [G. keras, horn]

keratoacanthoma (ker′a-to-ak′an-tho′ma)
A rapidly growing tumor that may be umbilicated, and usually occurs on exposed areas of the skin in elderly white men, which invades the dermis but remains localized and usually resolves spontaneously if untreated; microscopically, the nodule is composed of well-differentiated squamous epithelium with a central keratin mass that opens on the skin surface. [kerato- + G. akantha, thorn, +-oma, tumor]

keratoangioma (ker′a-to-an-je-o′ma)
SYN: angiokeratoma.

keratocele (ker′a-to-sel)
Hernia of Descemet membrane through a defect in the outer layers of the cornea. [kerato- + G. kele, hernia]

keratoconjunctivitis (ker′a-to-kon-jungk′ti-vi′tis)
Inflammation of the conjunctiva and of the cornea. atopic k. a chronic papillary inflammation, of the conjunctiva showing Trantas dots in a patient with a history of atopy. epidemic k. follicular conjunctivitis followed by subepithelial corneal infiltrates; often caused by adenovirus type 8, less commonly by other types. SYN: virus k.. flash k. SYN: ultraviolet k.. herpetic k. SYN: herpetic keratitis. microsporidian k. a form of k. often associated with immunosuppressed persons, such as those suffering from AIDS. k. sicca k. associated with decreased tears. SEE ALSO: Sjögren syndrome. SYN: dry eye syndrome, keratitis sicca. superior limbic k. inflammatory edema of the superior corneoscleral limbus. ultraviolet k. acute k. resulting from exposure to intense ultraviolet irradiation. SYN: actinic conjunctivitis, arc-flash conjunctivitis, flash k., ophthalmia nivalis, snow conjunctivitis, welder's conjunctivitis. vernal k. SYN: vernal conjunctivitis. virus k. SYN: epidemic k..

keratoconus (ker′a-to-ko′nus)
A conical protrusion of the cornea caused by thinning of the stroma; usually bilateral. SEE ALSO: Fleischer ring, Munson sign. SYN: conical cornea. [kerato- + G. konos, cone] circumscribed posterior k. congenital corneal defect characterized by a craterlike defect on the posterior corneal surface.

keratocricoid (ker′a-to-kri′koyd)
SYN: ceratocricoid.

keratocyst (ker′a-to-sist)
Odontogenic cyst derived from remnants of the dental lamina and appearing as a unilocular or multilocular radiolucency which may produce jaw expansion; epithelial lining is characterized microscopically by a uniform thickness, a corrugated superficial layer of parakeratin, and a prominent basal layer composed of palisaded columnar cells; associated with the bifid rib basal cell nevus syndrome. odontogenic k. (ke-ra′to-sist) a cyst of dental lamina origin with a high recurrence rate and well-defined histologic criteria of a corrugated parakeratin surface, uniformly thin epithelium, and a palisaded basal layer. One manifestation of the basal cell nevus syndrome.

keratocyte (ker′a-to-sit)
The fibroblastic stromal cell of the cornea.

keratoderma (ker′a-to-der′ma)
1. Any horny superficial growth. 2. A generalized thickening of the horny layer of the epidermis. [kerato- + G. derma, skin] k. blennorrhagica SYN: keratosis blennorrhagica. k. blennorrhagicum (blen-o-raj′i-kum) the scattered, thickened, hyperkeratotic skin lesions seen in Reiter syndrome. lymphedematous k. SYN: mossy foot. mutilating k. [MIM*124500] diffuse k. of the extremities, with the development during childhood of constricting fibrous bands around the middle phalanx of the fingers or toes that may lead to spontaneous amputation; there may be congenital deafness; autosomal dominant inheritance, caused by mutation in the gene for loricrin (LOR), a component of the epidermal differentiation complex on 1q. SYN: keratoma hereditarium mutilans, Vohwinkel syndrome. k. palmaris et plantaris SYN: palmoplantar k.. palmoplantar k. [MIM*148600 & MIM*244850] the occurrence of symmetrical diffuse or patchy areas of hypertrophy of the horny layer of the epidermis on the palms and soles; a group of ectodermal dysplasias of considerable variety, and either autosomal dominant or recessive inheritance. SYN: ichthyosis palmaris et plantaris, k. palmaris et plantaris, k. symmetrica, keratoma plantare sulcatum, keratosis palmaris et plantaris, tylosis palmaris et plantaris. k. plantare sulcatum hyperkeratosis and fissure formation on the soles. SYN: cracked heel. punctate k. [MIM*175860] horny papules over the palms, soles, and digits that develop central plugs; seen commonly in blacks; autosomal dominant inheritance. SYN: keratoma disseminatum, keratosis punctata. senile k. SYN: actinic keratosis. k. symmetrica SYN: palmoplantar k.. type III punctate palmoplantar k. SYN: acrokeratoelastoidosis.

keratodermatitis (ker′a-to-der-ma-ti′tis)
Inflammation with proliferation of the horny layer of the skin. [kerato- + G. derma, skin, + -itis, inflammation]

keratoectasia (ker′a-to-ek-ta′ze-a)
A bulging forward of the cornea. SYN: corneal ectasia, keratectasia.

keratoelastoidosis (ker′a-to-a-las′toy-do-sis)
Hyperkeratosis and degeneration of dermal elastic tissue. SEE ALSO: acrokeratoelastoidosis. [kerato- + Mod. L. elasticus, elastic, fr. G. elastikos, propulsive, fr. elauno, to drive + eidos, resemblance, + suffix -osis, condition] k. marginalis (mar-gin-al′is) hyperkeratosis and solar elastosis presenting as linear papules along the junction of the palms and dorsal surface of the hands in the elderly. [L. marginal]

keratoepithelioplasty (ker′a-to-ep-i-the′le-o-plas-te)
A surgical procedure for the repair of persistent corneal epithelial defects. All corneal epithelium is removed from the recipient cornea, and small pieces of donor cornea, with epithelium attached, are placed at the corneoscleral limbus. The donor corneal eplithelium grows and spreads out to cover the recipient cornea. [kerato- + epithelio- + G. plastos, formed]

keratogenesis (ker′a-to-jen′e-sis)
Production or origin of horny cells or tissue. [kerato- + G. genesis, production]

keratogenetic (ker′a-to-je-net′ik)
Relating to keratogenesis.

keratogenous (ker-a-toj′e-nus)
Causing a growth of cells that produce keratin and result in the formation of horny tissue, such as fingernails, scales, feathers, etc.

keratoglobus (ker-a-to-glo′bus)
Congenital anomaly consisting of an enlarged anterior segment of the eye. SYN: anterior megalophthalmos, megalocornea. [kerato- + L. globus, ball]

keratography (ker′ah-tog′ra-fe)
A record or portrayal of the cornea. See photokeratoscope, videokeratoscope. [kerato- + G. grapho, to write]

keratohyal (ker′a-to-hi′al)
SYN: ceratohyal.

keratohyalin (ker′a-to-hi′a-lin)
The substance in the large basophilic granules of the stratum granulosum of the epidermis rich in proline and sulfhydryl groups. [kerato- + hyalin]

keratoid (ker′a-toyd)
Resembling corneal tissue. [kerato- + G. eidos, resemblance]

keratoleptynsis (ker′a-to-lep-tin′sis)
1. SYN: gutter dystrophy of cornea. 2. An operation for removing the surface of the cornea and replacement by bulbar conjunctiva for cosmetic reasons. [kerato- + G. leptynsis, a making thin]

keratoleukoma (ker′a-to-loo-ko′ma)
A white corneal opacity. [kerato- + G. leukos, white, + -oma, growth]

keratolysis (ker-a-tol′i-sis)
1. Separation or loosening of the horny layer of the epidermis. 2. Specifically, a disease characterized by a shedding of the epidermis recurring at more or less regular intervals. SYN: deciduous skin. [kerato- + G. lysis, loosening] k. exfoliativa [MIM*270300] familial continual noninflammatory skin peeling characterized by a separation of stratum corneum in leaflike flakes occurring everywhere except on the palms and soles; autosomal recessive inheritance. SYN: erythema exfoliativa. pitted k. noninflammatory Gram-positive bacterial infection of the plantar surfaces producing small depressions in the stratum corneum, associated frequently with humidity and hyperhidrosis. SYN: k. plantare sulcatum. k. plantare sulcatum SYN: pitted k..

keratolytic (ker′a-to-lit′ik)
Relating to keratolysis.

keratoma (ker-a-to′ma)
1. SYN: callosity. 2. A horny tumor. [kerato- + G. -oma, tumor] k. disseminatum SYN: punctate keratoderma. k. hereditarium mutilans SYN: mutilating keratoderma. k. plantare sulcatum SYN: palmoplantar keratoderma. senile k. SYN: actinic keratosis.

keratomalacia (ker′a-to-ma-la′she-a)
Dryness with ulceration and perforation of the cornea, with absence of inflammatory reactions, occurring in cachectic children; results from severe vitamin A deficiency. SYN: xerotic keratitis. [kerato- + G. malakia, softness]

keratome (ker′a-tom)
A knife used for incising the cornea. SYN: keratotome.

keratometer (ker-a-tom′e-ter)
An instrument for measuring the curvature of the anterior corneal surface. SYN: ophthalmometer. [kerato- + G. metron, measure]

keratometry (ker-a-tom′e-tre)
Measurement of the radii of corneal curvature.

keratomileusis (ker′a-to-mi-loo′sis)
Surgical alteration of refractive error by changing the shape of a deep layer of the cornea: the anterior lamella is peeled back, frozen, and recarved on its back surface on a lathe; or, some of the corneal stroma can be removed from the bed with a laser or a knife. [coinage, prob. fr. G. keras (kerat-), horn, cornea, + smileusis, carving] laser-assisted in situ k. (LASIK) a refractive procedure to correct myopia by which a flap of cornea is made, excimer laser ablation of corneal stoma is performed, and the flap laid back in position.

keratomycosis (ker-a-to-mi-ko′sis)
Fungal infection of the cornea.

keratonosis (ker′a-to-no′sis)
Any abnormal noninflammatory, usually hypertrophic, affection of the horny layer of the skin. [kerato- + G. -osis, condition]

keratopachyderma (ker′a-to-pak-i-der′ma)
A syndrome of congenital deafness with development of hyperkeratosis of the skin of the palms, soles, elbows, and knees in childhood, and with bandlike constrictions of the fingers. [kerato- + G. pachys, thick, + derma, skin]

keratopathia (ker′a-to-path′e-a)
SYN: keratopathy. k. guttata wartlike endothelial excrescence on the posterior surface of the cornea.

keratopathy (ker-a-top′a-the)
Any corneal disease, damage, dysfunction, or abnormality. SYN: keratopathia. [kerato- + G. pathos, suffering, disease] band-shaped k. a horizontal, gray, interpalpebral opacity of the cornea that begins at the periphery and progresses centrally; occurs in hypercalcemia, chronic iridocyclitis, and Still disease. bullous k. edema of the corneal stroma and epithelium; occurs in Fuchs endothelial dystrophy, advanced glaucoma, iridocyclitis, and sometimes after intraocular lens implantation. chronic actinic k. SYN: climatic k.. climatic k. a bilateral, symmetrical corneal dystrophy caused by prolonged exposure to extremes of heat or cold; nodular opacities are limited to the interpalpebral area and vision is only mildly affected. SYN: chronic actinic k., climatic droplike k., Labrador k., spheroidal degeneration. climatic droplike k. SYN: climatic k.. filamentary k. formation of fine elongations of corneal epithelium in inflammation, edema, and degenerative states. infectious crystalline k. fernlike, needle-shaped deposits that may be seen in bacterial keratitis, particularly that due to α-hemolytic streptococci, under streptococcus. Labrador k. SYN: climatic k.. lipid k. occurrence of fats in an area of corneal vascularization. neuroparalytic k. corneal inflammation or ulceration associated with dysfunction of the ophthalmic branch of the trigeminal nerve. striate k. corneal stromal edema with formation of criss-cross tracts. vesicular k. corneal epithelial edema with formation of vacuoles.

keratophakia (ker′a-to-fak′e-a)
Implantation of a donor cornea or plastic lens within the corneal stroma to modify refractive error. SYN: keratophakic keratoplasty. [kerato- + G. phakos, lens]

keratoplasia (ker′a-to-pla′ze-a)
The formation or renewal of a horny layer. [kerato- + G. plasso; to fashion]

keratoplasty (ker′a-to-plas-te)
Any surgical modification of the cornea; the removal of a portion of the cornea containing an opacity and the insertion in its place of a piece of cornea of the same size and shape removed from elsewhere. SYN: corneal graft, corneal transplantation, corneal trepanation, trepanation of cornea, transplantation of cornea. [kerato- + G. plasso, to form] allopathic k. corneal transplant with donor material of glass, plastic, or other inert material. autogenous k. corneal transplant with donor material from the same individual. epikeratophakic k. SYN: epikeratophakia. heterogenous k. corneal transplant with donor material from another species. homogenous k. corneal transplant with donor material from another individual of the same species. keratophakic k. SYN: keratophakia. lamellar k., layered k. SYN: nonpenetrating k.. nonpenetrating k. k. in which only the anterior layer of the cornea is used (not a tectonic k.). SYN: lamellar k., layered k.. optical k. transplantation of transparent corneal tissue to replace a leukoma or scar that impairs vision. penetrating k. corneal transplant with replacement of all layers of the cornea, but retaining the peripheral cornea. SYN: perforating k.. perforating k. SYN: penetrating k.. refractive k. any procedure in which the shape of the cornea is modified, with the intent of changing the refractive error of the eye; for example, if the cornea is flattened, the eye becomes less myopic. See photorefractive keratectomy, keratophakia, lamellar k., thermokeratoplasty, keratomileusis, radial keratotomy. SYN: keratorefractive surgery. tectonic k. grafting to replace lost corneal tissue. total k. corneal transplant in which the entire cornea is removed and replaced.

keratoprosthesis (ker′a-to-pros-the′sis)
Replacement of the central area of an opacified cornea by plastic. [kerato- + G. prosthesis, addition]

keratorhexis, keratorrhexis (ker′a-to-rek′sis)
Rupture of the cornea, due to trauma or perforating ulcer. [kerato- + G. rhexis, a bursting]

keratorus (ker-a-to′rus)
Vaultlike corneal herniation with severe regular myopic astigmatism. [kerat- + L. torus, swelling, knot, bulge]

keratoscleritis (ker′a-to-skle-ri′tis)
Inflammation of both cornea and sclera.

keratoscope (ker′a-to-skop)
An instrument marked with lines or circles by means of which the corneal reflex can be observed. SYN: Placido da Costa disk. [kerato- + G. skopeo, to examine]

keratoscopy (ker-a-tos′ko-pe)
1. Examination of the reflections from the anterior surface of the cornea in order to determine the character and amount of corneal astigmatism. 2. A term first applied by Cuignet to his method of retinoscopy. [kerato- + G. skopeo, to examine]

keratosis, pl .keratoses (ker-a-to′sis, -sez)
Any lesion on the epidermis marked by the presence of circumscribed overgrowths of the horny layer. [kerato- + G. -osis, condition] actinic k. a premalignant warty lesion occurring on the sun-exposed skin of the face or hands in aged light-skinned persons; hyperkeratosis may form a cutaneous horn, and squamous cell carcinoma of low-grade malignancy may develop in a small proportion of untreated patients. SYN: senile keratoderma, senile keratoma, senile k., k. senilis, senile wart, solar k., verruca plana senilis, verruca senilis. arsenical k. multiple punctate keratoses, most commonly of the palms and soles but also of the fingers and proximal portions of the extremities, resulting from long-term arsenic ingestion; they resemble Bowen disease microscopically and may become squamous cell or basal cell carcinoma. k. blennorrhagica pustules and crusts associated with Reiter syndrome. SYN: keratoderma blennorrhagica. k. follicularis [MIM*124200] an autosomal dominant disorder characterized by eruption, beginning usually in late childhood, in which keratotic papules originating from both follicles and interfollicular epidermis of the trunk, face, scalp, and axillae become crusted and verrucous; the papules are often intensely pruritic. Microscopically, dyskeratotic cells termed corps ronds are seen in the epidermis. Longitudinal nail bands are frequent. SYN: Darier disease. inverted follicular k. a solitary benign epithelial tumor of infundibular hair follicle origin occurring on the face, consisting of a lobulated epidermal downgrowth of keratinizing squamous cells with a pattern of eddies or whorls. k. labialis thickening of stratum corneum on the lips. lichenoid k. a solitary benign papule or plaque, with microscopic features resembling lichen planus, occurring on sun-exposed or unexposed skin. SYN: lichen planus-like k.. lichen planus-like k. SYN: lichenoid k.. k. obturans an accretion of epithelia in the external auditory canal. SYN: laminated epithelial plug. k. palmaris et plantaris SYN: palmoplantar keratoderma. k. pilaris a common benign eruption consisting of scaly papules of the follicles; primarily affects the extensor surfaces of the arms and thighs. k. pilaris atrophicans faciei erythema and horny plugs of outer portions of the eyebrows with destruction of follicles; onset in early infancy. k. punctata SYN: punctate keratoderma. seborrheic k., k. seborrheica superficial, benign, verrucous, often pigmented, greasy lesions consisting of proliferating epidermal cells, resembling basal cells, enclosing horn cysts; they usually occur after the third decade. SYN: basal cell papilloma, seborrheic verruca. senile k., k. senilis SYN: actinic k.. solar k. SYN: actinic k.. tar k. warty lesions of the face and hands resulting from repeated, prolonged exposure to tar and pitch; also occurs as keratoacanthoma-like lesions that can become malignant, particularly on the scrotum.

keratosulfate (ker′a-to-sul-fat)
SYN: keratan sulfate.

keratotome (ker′a-to-tom)
SYN: keratome.

keratotomy (ker′a-tot′o-me)
1. Any incision through the cornea. 2. An operation making a partial thickness incision into the cornea to flatten it and reduce its refractive power in that meridian. [kerato- + G. tome, incision] delimiting k. incision in the cornea along the margin of an advancing ulcer. radial k. a k. with radial incisions around a clear central zone. A form of refractive keratoplasty used in the treatment of myopia. refractive k. modification of corneal curvature by means of corneal incisions to minimize hyperopia, myopia, or astigmatism.

keraunophobia (ke-raw′no-fo′be-a)
Morbid fear of thunder and lightning. [G. keraunos, thunderbolt, + phobos, fear]

Kerckring (Kerckringius)
Theodor, Dutch anatomist, 1640–1693. See K. center, K. folds, under fold, ossicle, K. valves, under valve.

kerion (ke′re-on)
A granulomatous secondarily infected lesion complicating fungal infection of the hair; typically, a raised boggy lesion. [G. k., honeycomb; a skin disease, fr. keros, beeswax]

Kerley
Peter J., English radiologist, 1900–1979. See K. B lines, under line.

kernel (ker′nel)
The central portion of the software expression of a mathematical algorithm, as in computed tomography. [O.E. cyrnel, a little corn]

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