Keratosis pilaris atrophicans (KPA) is a group of inherited disorders with three subtypes including (a) keratosis pilaris atrophicans faciei (KPAF), (b) atrophoderma vermiculatum (AV), and (c) keratosis follicularis spinulosa decalvans (KFSD). KPAF and AV present mainly on the face with KFSD often appearing on the eyebrow and AV most commonly seen on the cheeks, sparing the eyebrows and scalp. KFSD can affect the face, scalp, and trunk. Inheritance pattern can be autosomal dominant (KPAF, AV), recessive (AV), or X-linked (KFSD).
Incidence: very rare; KPAF is the most common subtype
Age: KPAF and KFSD in infancy; AV in childhood
Sex: males are more severely affected in KFSD
Abnormal follicular keratinization of the upper section of the hair follicle that may later result in atrophic follicular scarring.
Follicular plugging with erythema in early stages (Figure 33.1). Atrophic follicular scar formation with associated alopecia in later stages.
Keratosis pilaris: fine, sandpaper-like follicular papules on the arm of a young man
Keratosis pilaris, keratosis pilaris rubra, seborrheic dermatitis (KPAF), atopic dermatitis (KFSD), other etiologies of scarring alopecia (KFSD), acne scarring (AV), Rombo syndrome (AV), and KID syndrome (KFSD).
Dilated follicles with follicular hyperkeratosis and inflammation in early stages. Follicular fibrosis and atrophy in later stages.
The course is chronic with no spontaneous resolution. With time, the erythematous follicular hyperkeratotic papules involute into depressed atrophic follicular scars with alopecia.
There is no completely effective treatment for KPA. Multiple treatment options have been tried with only variable success. Patients should be counseled that therapy may not be effective.