title: [A mysterious question mark on the back].
authors.affiliation: johanna.hook-nikanne@huch.fi
authors.forename: J
authors.initials: J
authors.lastname: Höök-Nikanne
authors.forename: A L
authors.initials: AL
authors.lastname: Kariniemi
mesh_terms: D001415:Back; D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D017499:Porokeratosis / Q000175:diagnosis* / Q000235:genetics