Skin nonmelanocytic tumor
Benign (nonmelanotic) epidermal tumors or tumor-like lesions
Porokeratosis
Last author update: 1 August 2011
Last staff update: 24 April 2023 (update in progress)
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Porokeratosis
Table of Contents
Definition / general | Epidemiology | Microscopic (histologic) description | Differential diagnosisCite this page: Hamodat M. Porokeratosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skinnontumorporokeratosis.html. Accessed June 2nd, 2023.
Definition / general
- Rare disease, consists of an atrophic center bordered by a peripheral grooved keratotic ridge
Epidemiology
- 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
Microscopic (histologic) 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
Differential diagnosis
- Cornoid lamella formation: also seen in seborrheic warts, solar keratosis, veruca vulgaris, squamous cell carcinoma and basal cell carcinoma, porokeratotic eccrine nevi
