Chapter 24: Alopecia Areata (AA)

SUMMARY

• Alopecia areata (AA) is an autoimmune disorder of the hair follicle (HF), characterized by a reversible process of hair loss in which cytotoxic T-lymphocytes specifically attack the follicular unit, due to loss of the HF immuno-privilege.

• AA can involve only some follicles (patchy or diffused alopecia areata) or the whole scalp (alopecia areata totalis, AAT), or even all the body hairs (alopecia areata universalis, AAU), including eyelashes, eyebrows, and beard. The nail unit can also be involved.

TIPS FOR DIAGNOSIS

• The diagnosis of AA is usually made clinically, but in the last years trichoscopy played a primary role in terms of early detection and differential diagnosis.

• Trichoscopy can show several signs of active disease (broken hairs, exclamation marks hairs,), chronic disease (yellow dots), or recovery (short regrowing hairs,), being important in all the phases of the disease.

• A scalp biopsy is hardly ever needed but can be useful in suspect of trichotillomania, alopecia areata incognita, or cicatricial alopecia.

TIPS FOR TREATMENT

• The aim of therapy is to stop the disease activity and to obtain a (possibly complete) hair regrowth, an increasingly complex goal as the disease becomes more severe and extended (AAT or AAU);

• The most important medications used in the clinical practice are local or systemic corticosteroids and other immunosuppressants (cyclosporine, methotrexate, azathioprine, Janus-Kinase (JAK)-inhibitors) or local immunotherapy (diphenylcypropenone, squaric acid dibuthyesther, Anthralin).

DON’T FORGET

• AA can involve people of all age, sex and race, and the prognosis is often defined by age at the time of onset (being more severe in children).

• A whole scalp dermoscopy examination is always required, as the disease activity can be also detected in areas with no signs of alopecia, in addition to the periphery of the patches, as this can affect the clinical prognosis.

• Macroscopic photographs are also useful to monitor the disease and let the patients appreciate the (eventual) regrowth at follow-up.

PITFALLS AND CAUTIONS

• Laboratory exams may show associated autoimmune disorders, particularly thyroid disorders.

• Association with atopy is common (up to 30% of the cases).

• In the case of long-lasting corticosteroid usage, be careful about the long-term side effects (e.g., bone growth retardation or cortisol suppression in children).

• AA is a condition often involving the psychological sphere of patients, an expert’s support is recommended.

EXPERT PEARLS

• The treatment of AA can be challenging and often requires a combination therapy (with local and systemic drugs) in a long-term scenario, with frequent switches of different medications, to reach the goal of regrowth.

• Choice of treatment depends on the age (children/adults) and the severity of the disease (<50% or >50% scalp involvement), trichoscopy activity, previous treatments).

• Local and systemic JAK-inhibitors represents a therapeutic breakthrough for the disease, eventhough they are just a treatment and not a cure.

PATIENT EDUCATION POINTS

• The evolution of the AA is unpredictable and often characterized by hair loss periods (triggers ...