Alopecia Areata: Autoimmune Alopecia…

The first use of the term “Alopecia Areata” is attributed to the Polish physician John Jonston (1603-1675) in his book “Medicina Practica” published in 1664.  For more historical information on Alopecia Areata (AA) click HERE.  Alopecia areata is also referred to as Autoimmune Alopecia.  AA is characterized by rapid and complete hair loss in one or more round or oval patches ranging 1-5 cm in diameter, most frequently involving the scalp, bearded area, eyebrows, eyelashes and less frequently, other hairy areas of the body.  The incidence is 20 per 100,000 person years…about 2% of the general population.

A few resting hairs may be found within the patches, but the areas are often completely bare.  Additional signs include “exclamation point” hairs, which are tapered fractures of the hair shaft and nail pitting (see below) which is reported in about 10% of patients.  AA presents as an anagen effluvium with an inflammatory insult to the hair shaft and fracture of the anagen hair.  To review hair anatomy click HERE.   As the hair miniaturizes or converts from anagen to telogen the remaining lower portion of the hair rises above the level of the scalp, producing the exclamation point hair (Andrews’ Diseases of the Skin).  AA is associated with Down syndrome (patient above), atopic dermatitis, lichen planus and other autoimmune disorders such as systemic lupus erythematosus (SLE), thyroiditis, diabetes mellitus, myasthenia gravis and vitiligo.  Most cases, however, do not have any of these other disorders.  Twenty five percent of patients have a family history.  Complete loss of scalp hair is referred to as alopecia totalis and complete loss of all hair on the body is referred to as alopecia universalis.

On histology there is inflammation around the hair follicle comprised of T cells that attack the hair follicle through CD8(+)NK group 2D-positive (NKG2D(+)) T cells that induce a variety of cytokines and chemokines.

ETIOLOGY:  More recent studies suggest that AA may have a genetic basis.  A concordance rate of 55% is found in identical twins.  Genomic-wide association studies (GWAS) metanalysis have localized the HLA signal for AA to HLA-DRB1.  One locus harboring the genes encoding natural killer cell receptor D (NKG2D) is active in AA but not in other autoimmune disorders (Ref click HERE).

TREATMENT:  The available treatments are many.  As with many treatments, the more to choose from the less likely a response…it is very difficult to treat.  Traditionally many dermatologist treat smaller areas with intralesional steroids (first line of treatment), and this often works, but takes multiple injections.  For more advanced cases systemic steroids have been used with some success.  Topical treatments include minoxidil, topical steroids, and anthralin.  Topical sensitizers to induce contact sensitization inducing hair growth include dinitrochlorobenzene (DNCB) and diphencyprone.  Light box treatments (PUVA) may be useful but expose patients to other risks, such as increased risk of developing skin cancer.  Systemic agents include cyclosporine, methotrexate and sulfasalazine have been used.  308-nm xenon chloride eximer lasers have been reported to be beneficial.  Even botanicals have been used, including peony glucosides and glycyrrhizin.

HOPE:  There is much research on use of Janus Kinase (JAK) Inhibitors…and they are showing much promise.  A number of articles have been published on use of Tofacitinib.  To read more about JAK inhibitors click HERE.  To read more about AA click HERE and HERE.  To link to the Alopcia Areata Foundation, a wonderful support group, please click HERE.