Hyperkeratosis

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Hyperkeratosis
Classification and external resources
Lichen simplex chronicus - low mag.jpg
Micrograph showing hyperkeratosis. H&E stain.
ICD-10L85.9
ICD-9701.1
DiseasesDB20624
 
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Hyperkeratosis
Classification and external resources
Lichen simplex chronicus - low mag.jpg
Micrograph showing hyperkeratosis. H&E stain.
ICD-10L85.9
ICD-9701.1
DiseasesDB20624

Hyperkeratosis (from Ancient Greek: ὑπέρ (hyper, “over”); keratos - keratin) is thickening of the stratum corneum (the outermost layer of the epidermis), 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 Zelboraf.[medical citation needed]

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.[2]

Types[edit]

Follicular[edit]

Follicular hyperkeratosis dass (also called "Phrynoderma") 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.

This condition has been shown in several small-scale studies to respond well to supplementation with vitamins and fats rich in essential fatty acids. Some research suggests this is due mainly to E and B vitamins.[3] Vitamin A is also listed as connected to the pathology.[4]

By other specific site[edit]

Hereditary[edit]

Other[edit]

Hyperkeratosis of mucous membranes[edit]

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]

See also[edit]

References[edit]

  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. ^ drugs.com > Urea Cream (Prescribing Information) Revised: 04/2010 by Stratus Pharmaceuticals
  3. ^ Nadiger, HA (1980). "Role of vitamin E in the aetiology of phrynoderma (follicular hyperkeratosis) and its interrelationship with B-complex vitamins". The British journal of nutrition 44 (3): 211–4. doi:10.1079/bjn19800033. PMID 7437404. 
  4. ^ "Follicular hyperkeratosis". Dorland Medical Dictionary.
  5. ^ thedoctorsdoctor.com article
  6. ^ a b c Odom, Richard B.; Davidsohn, Israel; James, William D.; Henry, John Bernard; Berger, Timothy G.; Clinical diagnosis by laboratory methods; Dirk M. Elston (2006). Andrews' diseases of the skin: clinical dermatology. Saunders Elsevier. ISBN 0-7216-2921-0. 
  7. ^ a b c Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN 1-4160-2999-0. 
  8. ^ a b 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. "Keratosis pilaris: a common follicular hyperkeratosis.". 
  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.