Hyperkeratosis

Pronunciation|

* /ˌhaɪpərkɛrəˈtoʊsɪs/
(hyper- + kerato- + -osis)

Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,[1] and also usually accompanied by an increase in the granular layer. As the corneum layer normally varies greatly in thickness in different sites, some experience is needed to assess minor degrees of hyperkeratosis.

It can be caused by vitamin A deficiency or chronic exposure to arsenic.

Hyperkeratosis can also be caused by B-Raf inhibitor drugs such as Vemurafenib and Dabrafenib.[2]

It can be treated with urea-containing creams, which dissolve the intercellular matrix of the cells of the stratum corneum, promoting desquamation of scaly skin, eventually resulting in softening of hyperkeratotic areas.[3]

## Contents

* 1 Types
* 1.1 Follicular
* 1.2 By other specific site
* 1.3 Hereditary
* 1.4 Other
* 2 In mucous membranes
* 3 Etymology and pronunciation
* 4 See also
* 5 References
* 6 External links

## Types[edit | edit source]

* Flegel disease

* Flegel disease

* Hyperkeratosis of nipple and areola

### Follicular[edit | edit source]

Follicular hyperkeratosis, also known as keratosis pilaris (KP), is a skin condition characterized by excessive development of keratin in hair follicles, resulting in rough, cone-shaped, elevated papules. The openings are often closed with a white plug of encrusted sebum. When called phrynoderma the condition is associated with nutritional deficiency or malnourishment.

This condition has been shown in several small-scale studies to respond well to supplementation with vitamins and fats rich in essential fatty acids. Deficiencies of vitamin E,[4] vitamin A, and B-complex vitamins have been implicated in causing the condition.[5]

### By other specific site[edit | edit source]

* Plantar hyperkeratosis is hyperkeratosis of the sole of the foot. It is recommended to surgically remove the dead skin, to provide symptomatic relief.
* Hyperkeratosis of the nipple and areola is an uncommon benign, asymptomatic, acquired condition of unknown pathogenesis.[6]: 636

### Hereditary[edit | edit source]

* Epidermolytic hyperkeratosis (also known as "Bullous congenital ichthyosiform erythroderma,"[7] "Bullous ichthyosiform erythroderma,"[8]: 482 or "bullous congenital ichthyosiform erythroderma of Brocq"[9]) is a rare skin disease in the ichthyosis family affecting around 1 in 250,000 people. It involves the clumping of keratin filaments.[6]: 562 [10]
* Multiple minute digitate hyperkeratosis, a rare cutaneous condition, with about half of cases being familial
* Focal acral hyperkeratosis (also known as "Acrokeratoelastoidosis lichenoides,") is a late-onset keratoderma, inherited as an autosomal dominant condition, characterized by oval or polygonal crateriform papules developing along the border of the hands, feet, and wrists.[8]: 509
* Keratosis pilaris appears similar to gooseflesh, is usually asymptomatic and may be treated by moisturizing the skin.[11]

### Other[edit | edit source]

* Hyperkeratosis lenticularis perstans (also known as "Flegel's disease"[7]) is a cutaneous condition characterized by rough, yellow-brown keratotic, flat-topped papules.[6]: 639 [7]

## In mucous membranes[edit | edit source]

The term hyperkeratosis is often used in connection with lesions of the mucous membranes, such as leukoplakia. Because of the differences between mucous membranes and the skin (e.g. keratinizing mucosa does not have a stratum lucidum and non keratinizing mucosa does not have this layer or normally a stratum corneum or a stratum granulosum), sometimes specialized texts give slightly different definitions of hyperkeratosis in the context of mucosae. Examples are "an excessive formation of keratin (e.g., as seen in leukoplakia)"[12] and "an increase in the thickness of the keratin layer of the epithelium, or the presence of such a layer in a site where none would normally be expected."[13]

## Etymology and pronunciation[edit | edit source]

The word hyperkeratosis (/ˌhaɪpərˌkɛrəˈtoʊsɪs/) is based on the Ancient Greek morphemes hyper- \+ kerato- \+ -osis, meaning 'the condition of too much keratin'.

## See also[edit | edit source]

* List of dermatology terminology

## References[edit | edit source]

1. ↑ Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) Robbins & Cotran Pathologic Basis of Disease (7th ed.). Saunders. Page 1230. ISBN 0-7216-0187-1.
2. ↑ Niezgoda, Anna; Niezgoda, Piotr; Czajkowski, Rafal (2015) Novel Approaches to Treatment of Advanced Melanoma: A Review of Targeted Therapy and Immunotherapy BioMed Research International
3. ↑ drugs.com > Urea Cream (Prescribing Information) Archived 2017-01-18 at the Wayback Machine Revised: 04/2010 by Stratus Pharmaceuticals
4. ↑ Nadiger, HA (1980). "Role of vitamin E in the aetiology of phrynoderma (follicular hyperkeratosis) and its interrelationship with B-complex vitamins". British Journal of Nutrition. 44 (3): 211–4. doi:10.1079/bjn19800033. PMID 7437404.
5. ↑ "Hyperkeratosis". Dorland's Medical Dictionary for Health Consumers. 2007. Archived from the original on 2015-09-09. Retrieved 2015-08-10.
6. ↑ 6.0 6.1 6.2 James, William D.; Berger, Timothy G.; Elston, Dirk M.; et al. (2006). "Clinical diagnosis by laboratory methods". Andrews' diseases of the skin: clinical dermatology (10th ed.). Saunders Elsevier. ISBN 0-7216-2921-0.
7. ↑ 7.0 7.1 7.2 Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 978-1-4160-2999-1.
8. ↑ 8.0 8.1 Freedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN 0-07-138076-0.
9. ↑ synd/1036 at Who Named It?
10. ↑ Cheng J, Syder AJ, Yu QC, Letai A, Paller AS, Fuchs E (September 1992). "The genetic basis of epidermolytic hyperkeratosis: a disorder of differentiation-specific epidermal keratin genes". Cell. 70 (5): 811–9. doi:10.1016/0092-8674(92)90314-3. PMID 1381287.
11. ↑ Hwang, Schwartz (Sep 2008). "Keratosis pilaris: a common follicular hyperkeratosis". Cutis. 82 (3): 177–80. PMID 18856156.
12. ↑ Mosby's Dental Dictionary
13. ↑ Tyldesley WR, Field A, Longman L (2003). Tyldesley's Oral medicine (5th ed.). Oxford: Oxford University Press. ISBN 0192631470.

## External links[edit | edit source]

Classification|

* ICD-10: L85.9
* ICD-9-CM: 701.1
* DiseasesDB: 20624
* SNOMED CT: 20637002

|

* v
* t
* e

Skin lesion terminology

Macroscopic|

| Primary lesions|

* flat
* Macule
* Patch
* elevated
* Papule
* Nodule
* Plaque
* fluid
* Vesicle
* Bulla
* Pustule
* Ulcer
* Erosion
* Telangiectasia

* Special initial lesions : Burrow
* Tunnel
* Comedo
* Scutulum
* Target lesion
* Herald patch
* Wheal

|

Secondary lesions|

* Scale
* Crust
* Lichenification
* Excoriation
* Induration
* Atrophy

Microscopic|

* keratin: Hyperkeratosis
* Parakeratosis
* Dyskeratosis

* Hypergranulosis
* Acanthosis
* Papillomatosis
* Acantholysis
* Spongiosis
* Hydropic swelling
* Exocytosis
* Vacuolization
* Erosion
* Ulceration
* Lentiginous

* v
* t
* e

Cutaneous keratosis, ulcer, atrophy, and necrobiosis

Epidermal thickening|

* keratoderma: Keratoderma climactericum
* Paraneoplastic keratoderma
* Acrokeratosis paraneoplastica of Bazex
* Aquagenic keratoderma
* Drug-induced keratoderma
* psoriasis
* Keratoderma blennorrhagicum

* keratosis: Seborrheic keratosis
* Clonal seborrheic keratosis
* Common seborrheic keratosis
* Irritated seborrheic keratosis
* Seborrheic keratosis with squamous atypia
* Reticulated seborrheic keratosis
* Dermatosis papulosa nigra
* Keratosis punctata of the palmar creases

* other hyperkeratosis: Acanthosis nigricans
* Confluent and reticulated papillomatosis
* Callus
* Ichthyosis acquisita
* Arsenical keratosis
* Chronic scar keratosis
* Hyperkeratosis lenticularis perstans
* Hydrocarbon keratosis
* Hyperkeratosis of the nipple and areola
* Inverted follicular keratosis
* Lichenoid keratosis
* Multiple minute digitate hyperkeratosis
* PUVA keratosis
* Reactional keratosis
* Stucco keratosis
* Thermal keratosis
* Viral keratosis
* Warty dyskeratoma
* Waxy keratosis of childhood

* other hypertrophy: Keloid
* Hypertrophic scar
* Cutis verticis gyrata

Necrobiosis/granuloma|

| Necrobiotic/palisading|

* Granuloma annulare
* Perforating
* Generalized
* Subcutaneous
* Granuloma annulare in HIV disease
* Localized granuloma annulare
* Patch-type granuloma annulare
* Necrobiosis lipoidica
* Annular elastolytic giant-cell granuloma
* Granuloma multiforme
* Necrobiotic xanthogranuloma
* Palisaded neutrophilic and granulomatous dermatitis
* Rheumatoid nodulosis
* Interstitial granulomatous dermatitis/Interstitial granulomatous drug reaction

|

Foreign body granuloma|

* Beryllium granuloma
* Mercury granuloma
* Silica granuloma
* Silicone granuloma
* Zirconium granuloma
* Soot tattoo
* Tattoo
* Carbon stain

Other/ungrouped|

* eosinophilic dermatosis
* Granuloma faciale

Dermis/
localized CTD|

| Cutaneous lupus
erythematosus|

* chronic: Discoid
* Panniculitis

* subacute: Neonatal

* ungrouped: Chilblain
* Lupus erythematosus–lichen planus overlap syndrome
* Tumid
* Verrucous
* Rowell's syndrome

|

Scleroderma/
Morphea|

* Localized scleroderma
* Localized morphea
* Morphea–lichen sclerosus et atrophicus overlap
* Generalized morphea
* Atrophoderma of Pasini and Pierini
* Pansclerotic morphea
* Morphea profunda
* Linear scleroderma

Atrophic/
atrophoderma|

* Lichen sclerosus
* Anetoderma
* Schweninger–Buzzi anetoderma
* Jadassohn–Pellizzari anetoderma
* Atrophoderma of Pasini and Pierini
* Acrodermatitis chronica atrophicans
* Semicircular lipoatrophy
* Follicular atrophoderma
* Linear atrophoderma of Moulin

Perforating|

* Kyrle disease
* Reactive perforating collagenosis
* Elastosis perforans serpiginosa
* Perforating folliculitis
* Acquired perforating dermatosis

Skin ulcer|

* Pyoderma gangrenosum

Other|

* Calcinosis cutis
* Sclerodactyly
* Poikiloderma vasculare atrophicans
* Ainhum/Pseudo-ainhum

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