Chapter 158: Alopecia Areata

Patient Story

An 8-year-old Hispanic girl was brought to her physician by her mother, who noticed two bald spots on the back of her daughter’s scalp while brushing her hair. The child had no itching or pain. The mother was more worried that her beautiful girl would become bald. The girl was pleased that the bald spots could be completely covered with her long hair, as she did not want anyone to see them. The child was otherwise healthy. When the mother lifted the hair in the back, two round areas of hair loss were evident (Figure 158-1). On close inspection, there was no scaling or scarring. The mother and child were reassured that alopecia areata (AA) is a condition in which the hair is likely to regrow without treatment. Neither of them wanted intralesional injections or topical therapies. During a well-child examination 1 year later, it was noted that the girl’s hair had fully regrown.¹

Introduction

AA is a common disorder that causes patches of hair loss without inflammation or scarring. The areas of hair loss are often round and the scalp is often very smooth at the site of hair loss.

Synonyms

Alopecia totalis involves the whole scalp. Alopecia universalis (AU) involves the whole scalp, head, and body (Figure 158-2). Limited alopecia areata on the scalp is called “patchy” alopecia areata or patch AA.

Epidemiology

• Alopecia areata affects approximately 0.2 percent of the population at any given time with approximately 1.7 percent of the population experiencing an episode during their lifetime.^2,3

• Males and females are equally affected.

• Patients with alopecia totalis and/or universalis were younger at the age of onset than those with patchy AA, were more likely to have atopic dermatitis, thyroid disease, and had a greater number of relatives affected by AA.⁴

Etiology and Pathophysiology

• The etiology is unknown but experts presume that the AA spectrum of disorders is secondary to an autoimmune phenomenon involving antibodies, T cells, and cytokines.

Risk Factors