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porokeratosis
Epidemiology:
- onset is during the 3rd or 4th decades of life
- cases presenting in childhood & at advanced age have been reported
Pathology:
- clonal disorder of keratinization
- dyskeratotic cells in the underlying epidermis
- cornoid lamella, a thin column of closely stacked, parakeratotic cells extending through the stratum corneum with a thin or absent stratum granulosum
Genetics:
- disseminated superficial porokeratosis can occur via autosomal dominant inheritance or can occur sporadically
- linear porokeratosis;
- second-hit postzygotic mutations in genes that encode enzymes within the mevalonate biosynthesis pathway [3]
- PMVK c.329G>A, PMVK c.79G>T, PMVK c.379C>T
- MVD (c.70 + 5G>A), MVD (c.811_815del, p.F271Afs*33 frameshift)
Clinical manifestations:
- multiple hyperpigmented plaques involving the face, trunk, & bilateral upper extremeties & lower extremities
- lesions had well-defined, threadlike borders & central atrophy (image [4]
Management:
- treatment is difficult, relapses are common
- topical agents include
- glucocorticoids
- retinoids
- vitamin D3 analogs,
- 5-fluorouracil
- tacrolimus
- compounded topical cholesterol*, 2%, & lovastatin*, 2%
- systemic treatment options include
- oral retinoids
- methotrexate
- several laser & light-based therapies have been used with variable success
- excimer, photodynamic therapy
- erbium:yttrium-aluminum-garnet laser
- carbon dioxide laser
* cholesterol is an end product of the mevalonate pathway & lovastatin inhibits HMG CoA reductase in the formation of mevalonate
General
skin disease (dermatologic disorder, dermatopathy, dermatosis)
References
- Spencer LV and Elston DM
eMedicine: Porokeratosis
http://emedicine.medscape.com/article/1059123-overview
- Wikipedia: Porokeratosis
http://en.wikipedia.org/wiki/Porokeratosis
- Atzmony L, Khan HM, Lim YH et al
Second-Hit, Postzygotic PMVK and MVD Mutations in Linear Porokeratosis
JAMA Dermatol. Published online April 3, 2019.
PMID: 30942823
https://jamanetwork.com/journals/jamadermatology/fullarticle/2729597
- Muradia I, Khullar G, Pareek V
Images in Dermatology. Porokeratosis.
JAMA Dermatol. 2023;159(2):209
PMID: 36515921
https://jamanetwork.com/journals/jamadermatology/fullarticle/2799340