Porokeratosis is a specific disorder of keratinization that is characterized histologically by the presence of a cornoid lamella, a thin column of closely stacked, parakeratotic cells extending through the stratum corneum with a thin or absent granular layer.[1]: 532
Porokeratosis may be divided into the following clinical types:[1]: 532
Plaque-type porokeratosis (also known as "Classic porokeratosis" and "Porokeratosis of Mibelli"[2]) is characterized by skin lesions that start as small, brownish papules that slowly enlarge to form irregular, annular, hyperkeratotic or verrucous plaques.[1]: 533 [3]: 566 Sometimes they may show gross overgrowth and even horn-like structures may develop.[4] Skin malignancy, although rare, is reported from all types of porokeratosis. Squamous cell carcinomas have been reported to develop in Mibelli's type porokeratosis over partianal areas involving anal mucosa. This was the first report mentioning mucosal malignancy in any form of porokeratosis.[4]
Disseminated superficial porokeratosis is a more generalized processes and involves mainly the extremities in a bilateral, symmetric fashion.[1]: 533 In about 50% of cases, skin lesions only develop in sun-exposed areas, and this is referred to as disseminated superficial actinic porokeratosis[1]: 533
Porokeratosis palmaris et plantaris disseminata is characterized by skin lesions that are superficial, small, relatively uniform, and demarcated by a distinct peripheral ridge of no more than 1mm in height.[1]: 534 [2]: 1668 [3]: 567
Linear porokeratosis is characterized clinically skin lesions are identical to those of classic porokeratosis, including lichenoid papules, annular lesions, hyperkeratotic plaques with central atrophy, and the characteristic peripheral ridge.[1][2]: 1668 [3]: 567
Punctate porokeratosis is a skin condition associated with either classic porokeratosis or linear porokeratosis types of porokeratosis, and is characterized by multiple, minute, and discrete punctate, hyperkeratotic, seed-like skin lesions surrounded by a thin, raised margin on the palms and soles.[1]: 535 [2]: 1668
Porokeratosis plantaris discreta is a skin condition that occurs in adults, with a 4:1 female preponderance, characterized by a sharply marginated, rubbery, wide-based papules.[3]: 213 It is also known as "Steinberg's lesion".[5] It was characterized in 1970.[6]
Micrograph of a case of porokeratosis showing a characteristic cornoid lamella (dark pink/red structure in the right/upper portion of the image). H&E stain.
Porokeratosis has a characteristic histomorphologic feature known as a cornoid lamella.
^Atzmony L, Khan HM, Lim YH, Paller AS, Levinsohn JL, Holland KE, Mirza FN, Yin E, Ko CJ, Leventhal JS, Choate KA (2019) Second-Hit, Postzygotic PMVK and MVD Mutations in Linear Porokeratosis. JAMA Dermatol
External linksedit
Database of rare diseases at Orphanet
December 20, 2023
porokeratosis, specific, disorder, keratinization, that, characterized, histologically, presence, cornoid, lamella, thin, column, closely, stacked, parakeratotic, cells, extending, through, stratum, corneum, with, thin, absent, granular, layer, porokeratosis, . Porokeratosis is a specific disorder of keratinization that is characterized histologically by the presence of a cornoid lamella a thin column of closely stacked parakeratotic cells extending through the stratum corneum with a thin or absent granular layer 1 532 PorokeratosisA porokeratosis lesion in a patient with disseminated superficial actinic porokeratosis SpecialtyPediatrics dermatology Contents 1 Types 2 Genetics 3 Diagnosis 3 1 Pathology 4 Treatment 5 See also 6 References 7 External linksTypes editPorokeratosis may be divided into the following clinical types 1 532 Plaque type porokeratosis also known as Classic porokeratosis and Porokeratosis of Mibelli 2 is characterized by skin lesions that start as small brownish papules that slowly enlarge to form irregular annular hyperkeratotic or verrucous plaques 1 533 3 566 Sometimes they may show gross overgrowth and even horn like structures may develop 4 Skin malignancy although rare is reported from all types of porokeratosis Squamous cell carcinomas have been reported to develop in Mibelli s type porokeratosis over partianal areas involving anal mucosa This was the first report mentioning mucosal malignancy in any form of porokeratosis 4 Disseminated superficial porokeratosis is a more generalized processes and involves mainly the extremities in a bilateral symmetric fashion 1 533 In about 50 of cases skin lesions only develop in sun exposed areas and this is referred to as disseminated superficial actinic porokeratosis 1 533 Porokeratosis palmaris et plantaris disseminata is characterized by skin lesions that are superficial small relatively uniform and demarcated by a distinct peripheral ridge of no more than 1mm in height 1 534 2 1668 3 567 Linear porokeratosis is characterized clinically skin lesions are identical to those of classic porokeratosis including lichenoid papules annular lesions hyperkeratotic plaques with central atrophy and the characteristic peripheral ridge 1 2 1668 3 567 Punctate porokeratosis is a skin condition associated with either classic porokeratosis or linear porokeratosis types of porokeratosis and is characterized by multiple minute and discrete punctate hyperkeratotic seed like skin lesions surrounded by a thin raised margin on the palms and soles 1 535 2 1668 Porokeratosis plantaris discreta is a skin condition that occurs in adults with a 4 1 female preponderance characterized by a sharply marginated rubbery wide based papules 3 213 It is also known as Steinberg s lesion 5 It was characterized in 1970 6 Genetics editLinear porokeratosis has been associated with mutations in the PMVK and MVD genes 7 The PMVK gene encodes the enzyme phosphomevalonate kinase and the MVD gene encodes the enzyme diphosphomevalonate decarboxylase Diagnosis editPathology edit nbsp Micrograph of a case of porokeratosis showing a characteristic cornoid lamella dark pink red structure in the right upper portion of the image H amp E stain Porokeratosis has a characteristic histomorphologic feature known as a cornoid lamella Treatment editDermabrasionSee also editList of cutaneous conditions List of cutaneous conditions associated with increased risk of nonmelanoma skin cancerReferences edit a b c d e f g h Freedberg et al 2003 Fitzpatrick s Dermatology in General Medicine 6th ed McGraw Hill ISBN 0 07 138076 0 a b c d Rapini Ronald P Bolognia Jean L Jorizzo Joseph L 2007 Dermatology 2 Volume Set St Louis Mosby p 1668 ISBN 978 1 4160 2999 1 a b c d James William Berger Timothy Elston Dirk 2005 Andrews Diseases of the Skin Clinical Dermatology 10th ed Saunders ISBN 0 7216 2921 0 a b Familial disseminated plaque type porokeratosis with multiple horns and squamous cell carcinoma involving anal skin Archived from the original on 2020 11 26 Retrieved 2013 09 01 Lemont H 2008 What s your diagnosis Porokeratosis plantaris discreta Steinberg s lesion J Am Podiatr Med Assoc 98 4 337 8 doi 10 7547 0980337 PMID 18685058 Taub J Steinberg MD 1970 Porokeratosis plantaris discreta a previously unrecognized dermatopathological entity Int J Dermatol 9 2 83 90 doi 10 1111 j 1365 4362 1970 tb04584 x PMID 5426632 S2CID 40802489 Atzmony L Khan HM Lim YH Paller AS Levinsohn JL Holland KE Mirza FN Yin E Ko CJ Leventhal JS Choate KA 2019 Second Hit Postzygotic PMVK and MVD Mutations in Linear Porokeratosis JAMA DermatolExternal links editDatabase of rare diseases at Orphanet NIH s Genetic and Rare Diseases Information Center Retrieved from https en wikipedia org w index php title Porokeratosis amp oldid 1167195791, wikipedia, wiki, book, books, library,
