Keratoacanthoma-Like Inverted Follicular Keratosis:a Case Report and Literature Review
LIU Jing
CUI Lin
ZHAO Liping
ZHANG Shifa
Abstract：One case of keratoacanthoma-like inverted follicular keratosis is reported.A 34-year-old man presented with a 1-month history of a gradually enlarging,asymptomatic,dark-brown nodule on the right back.Occasional surface scaling was noted.Dermatologic examination revealed a well-circumscribed,crateriform papulonodule with a slightly erythematous rim and a central keratin plug.The lesion was completely excised.Histopathology showed an exophytic and endophytic papillomatous squamous proliferation extending into the mid-dermis,focally connected to a follicular(infundibular)structure,with slight inward curving of the epithelial edges.The epidermis exhibited hyperkeratosis with areas of parakeratosis and focal surface defect;the granular layer was diminished or absent.Basaloid cells at the periphery displayed palisading.The center contained pale outer root sheath-like cells admixed with eosinophilic keratinocytes forming numerous squamous eddies,large keratin plugs,and horn cysts.Only scant granular cells were observed;cytologic atypia was minimal,and no atypical mitoses were identified.The surrounding dermis showed a mononuclear inflammatory infiltrate,dilated small vessels,and thickened collagen bundles.These features supported a diagnosis of keratoacanthoma-like inverted follicular keratosis.The postoperative course was uneventful,and no recurrence was observed during 12 months of follow-up.
Keywords：inverted follicular keratosiskeratoacanthoma-likehistopathologycase report
Publication Date：2026-02-10
Online Publishing Date：2026-03-17(First online date of this platform, not the publication date of the document)
Pages：3( 86-88 )