Keratosis follicularis spinulosa decalvans (KFSD) is a form of ichthyosis characterized by hardening of the skin around the hair follicles eventually leading to baldness (alopecia) and scarring. During infancy, keratosis begins on the face and moves to the extremities and trunk by childhood. Around puberty, alopecia of the scalp and eyebrows develops. KFSD is a rare X-linked disease that affects more males than females.