Squamous Hyperplasia



Squamous Hyperplasia


Antonio L. Cubilla, MD

Alcides Chaux, MD

Elsa F. Velazquez, MD





Key Facts


Terminology



  • Thickening of mucosal squamous epithelium without atypia


  • Most common epithelial alteration associated with penile cancer


  • Frequently associated with differentiated PeIN


  • Found in association with usual, papillary, and verrucous SCC (HPV-unrelated variants of SCC)


Macroscopic Features



  • Whitish areas with irregular borders


Microscopic Pathology



  • Acanthosis with hyperkeratosis


  • Normal maturation with no atypias


  • Parakeratosis is uncommon


  • Koilocytes are absent


  • Merging of SH with PeIN &/or invasive SCC is common finding


  • Flat squamous hyperplasia is most common pattern


  • Other subtypes include papillary, pseudoepitheliomatous, and verrucous


  • Mixed forms represent about 1/3 of cases


Top Differential Diagnoses



  • Differentiated PeIN


  • Warty PeIN


  • Basaloid PeIN


  • Warty/basaloid PeIN


  • Pseudohyperplastic SCC


  • Verruciform xanthoma


  • Warty, papillary, and verrucous carcinomas







Squamous hyperplasia typically presents as whitish pearly areas image with irregular borders merging with an adjacent in situ or invasive component image.






Squamous hyperplasia is characterized by acanthosis image, retained epithelial maturation, absence of cytologic atypia, hyperkeratosis image, and a flat surface.


TERMINOLOGY


Abbreviations



  • Squamous hyperplasia (SH), squamous cell carcinoma (SCC), penile intraepithelial neoplasia (PeIN)


Definitions



  • Thickening of mucosal squamous epithelium without cytologic atypia


ETIOLOGY/PATHOGENESIS


Pathogenesis



  • Unknown


  • Reactive condition rather than specific entity


  • Most common epithelial change associated with penile cancer


  • Almost all keratinizing SCC have associated SH


  • May be associated with reactive inflammatory conditions


CLINICAL ISSUES


Site



  • SH may affect any penile mucosal compartment


Presentation



  • Usually found in continuity or slightly distant from in situ or invasive SCC


  • Distinction between SH and normal mucosa may be subtle


  • Inapparent lesions may be better visualized with acetic acid (peniscopy)


  • Clinically, it may be difficult to distinguish from PeIN


  • Micaceous balanitis and penile horn are clinically florid forms of SH with prominent hyperkeratosis


Treatment



  • Benign epithelial change and usually no treatment is required


Prognosis



  • May be precursor lesion of HPV-unrelated variants of SCC, but more studies are required to confirm this hypothesis


MACROSCOPIC FEATURES


General Features



  • Whitish areas with irregular borders


  • Slightly raised areas with pearly appearance


MICROSCOPIC PATHOLOGY


Histologic Features



  • Acanthosis with orthokeratotic hyperkeratosis


  • Normal epithelial maturation


  • Chronic inflammation may be present


  • Absence of cytologic atypia


  • Absent koilocytosis


  • Minimal to absent parakeratosis


  • Absent intraepithelial keratin whorls (pearls)


  • Associated with lichen sclerosus in some cases


  • Frequently associated with differentiated PeIN


  • Usually found in association with usual, papillary, and verrucous SCC (HPV-unrelated variants of SCC)


  • Rarely present adjacent to condylomatous (warty) and basaloid SCC


  • Merging of SH with PeIN &/or invasive SCC is common finding


Histological Subtypes



  • Flat



    • Most common subtype


    • Nonatypical acanthosis


    • Hyperkeratosis with orthokeratosis



    • Linear interface between basal layer and stroma


  • Papillary



    • Represents minority of cases


    • Serrated appearance on low-power view


    • Jagged interface with underlying stroma


    • Nonatypical acanthosis with short hyperkeratotic papillae


  • Pseudoepitheliomatous



    • Unusual pattern of SH


    • Acanthosis


    • Downward elongated proliferation of rete ridges that appear detached from epithelium


    • Regular epithelial nests with peripheral palisading


    • Stromal reaction is not prominent


    • Typically associated with papillary SH


  • Verrucous



    • Present adjacent to verrucous carcinoma


    • Marked acanthosis with no atypia


    • Hyperkeratosis with hypergranulosis


    • Slight papillomatosis


  • Mixed



    • 2nd most common type


    • Presence of mixed areas of flat and papillary SH


DIFFERENTIAL DIAGNOSIS


Differentiated PeIN



  • Acanthosis, parakeratosis


  • Aberrant keratinization with cytologic atypia


  • Retained squamous maturation

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Jul 7, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Squamous Hyperplasia

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