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 is 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.
Follicular hyperkeratosis, also known as keratosis pilaris (KP), is a skin condition characterized by excessive development of keratininhair 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.
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]
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]
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]
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]
Nasodigitic hyperkeratosis in dogs may be idiopathic, secondary to an underlying disease, or due to congenital abnormalities in the normal anatomy of the nose and fingertips.
In the case of congenital anatomical abnormalities, contact between the affected area and rubbing surfaces is impaired. It is roughly the same with finger pads — in animals with an anatomical abnormality, part of the pad is not in contact with rubbing surfaces and excessive keratin deposition is formed. The idiopathic form of nasodigitic hyperkeratosis in dogs develops from unknown causes and is more common in older animals (senile form).[14][15] Of all dog breeds, Labradors, Golden Retrievers, Cocker Spaniels, Irish Terriers, Bordeaux Dogs are the most prone to hyperkeratosis.[16]
Since the deposition of excess keratin cannot be stopped, therapy is aimed at softening and removing it. For moderate to severe cases, the affected areas should be hydrated (moisturised) with warm water or compresses for 5-10 minutes. Softening preparations are then applied once a day until the excess keratin is removed.
In dogs with severe hyperkeratosis and a significant excess of keratin, it is removed with scissors or a blade. After proper instructions, pet owners are able to perform this procedure at home, and it may be the only method of correction.[17]
^Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) Robbins & Cotran Pathologic Basis of Disease (7th ed.). Saunders. Page 1230. ISBN0-7216-0187-1.
^Niezgoda, Anna; Niezgoda, Piotr; Czajkowski, Rafal (2015) Novel Approaches to Treatment of Advanced Melanoma: A Review of Targeted Therapy and Immunotherapy BioMed Research International
^"Hyperkeratosis". Dorland's Medical Dictionary for Health Consumers. 2007.
^ abcJames, 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. ISBN0-7216-2921-0.
^ abcRapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. ISBN978-1-4160-2999-1.
^ abFreedberg, et al. (2003). Fitzpatrick's Dermatology in General Medicine. (6th ed.). McGraw-Hill. ISBN0-07-138076-0.
