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Other dermatoses


Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 1 August 2011, last major update August 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● Rare disease, consists of an atrophic center bordered by a peripheral grooved keratotic ridge


● Six major categories: classic, localized, linear, punctuate, disseminated superficial porokeratosis and disseminated superficial actinic porokeratosis
● May be associated with a slight increase in neoplasia (basal cell and squamous cell carcinoma, Bowen's disease)
● May develop against a background of solid organ transplantation or blood transfusion, possibly related to hepatitis C infection

Micro description

● Recommended to biopsy peripheral grooved ridge to see classic features
● Keratin-filled epidermal invagination with an angulated, parakeratotic tier (cornoid lamella)
● Epithelium deep to the tier is vacuolated and devoid of a granular cell layer
● Adjacent epithelium towards the center is either atrophic, normal thickness or acanthotic
● Dyskeratotic cells may be seen
● Liquefactive degeneration of the basal cell layer is present; may be conspicuous cytoid bodies
● Dermis shows a non-specific inflammatory cell infiltrate with telangiectatic vessels
● In actinic variant, is often solar elastosis and atrophy of adjacent epidermis

Micro images

Contributed by Angel Fernandez-Flores, MD, PhD, Hospital El Bierzo and Clinica Ponferrada, Spain

Differential diagnosis

● Cornoid lamella formation also seen in seborrheic warts, solar keratosis, veruca vulgaris, squamous cell carcinoma and basal cell carcinoma, porokeratotic eccrine nevi

End of Skin-nontumor > Other dermatoses > Porokeratosis

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