title: Dermoscopy of inverted follicular keratosis: study of 12 cases.
abstract: BACKGROUND
  Inverted follicular keratosis (IFK) is an uncommon benign tumour of the follicular infundibulum, which is often misdiagnosed clinically as other keratinizing tumours, and commonly diagnosed correctly by histopathology. There are few reports about the dermoscopic findings of this lesion.
  
  
  OBJECTIVE
  To evaluate the dermoscopic features of IFK.
  
  
  METHODS
  The dermoscopic structures and patterns in digital dermoscopic images of 12 histopathologically confirmed cases of IFK collected from 5 hospitals in Spain were evaluated.
  
  
  RESULTS
  A keratoacanthoma (KA)-like pattern composed of central keratin surrounded by hairpin vessels in a radial arrangement was the most common pattern in IFK (58.3%). The second most common pattern was composed of a yellowish-white amorphous central area surrounded by vascular structures in a radial arrangement (33.3%). The remaining case showed a pattern composed of a yellowish-white amorphous central area with milky red globules. Vascular structures were present in all cases, with a monomorphic pattern in seven cases and a polymorphic pattern in five, mainly with radial arrangement. Arborizing vessels, linear irregular vessels, corkscrew vessels and milky red globules were present in some cases.
  
  
  CONCLUSIONS
  We describe the two main patterns of IFK. Lesions with a KA-like pattern are clinically and dermoscopically undistinguishable from KA and squamous cell carcinoma. Cases with a polymorphic vascular pattern could be confused with malignant tumours, including basal cell carcinoma and amelanotic melanoma.
authors.affiliation: Dermatology, Hospital Son Llatzer, Palma Mallorca, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Llambrich
authors.affiliation: Pathology Departments, Hospital Son Llatzer, Palma Mallorca, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Zaballos
authors.affiliation: Dermatology, Hospital Son Llatzer, Palma Mallorca, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Taberner
authors.affiliation: Dermatology Department, Hospital Sant Pau i Santa Tecla, Tarragona, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Terrasa
authors.affiliation: Dermatology Department, Hospital Universitario de Alicante, Alicante, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Bañuls
authors.affiliation: Dermatology Department, Clínica Dermatológica Internacional and Clínica Ruber, Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Pizarro
authors.affiliation: Department of Dermatology, Melanoma Unit, Hospital Clinic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.|Centro de Investigación Biomédica en Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Malvehy
authors.affiliation: Department of Dermatology, Melanoma Unit, Hospital Clinic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.|Centro de Investigación Biomédica en Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Puig
mesh_terms: D000328:Adult; D000368:Aged; D046169:Dermoscopy; D005153:Facial Neoplasms / Q000473:pathology; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology*; D006801:Humans; D007642:Keratosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012878:Skin Neoplasms / Q000473:pathology*