Alopecia Areata ICD-10: L63.9

Autoimmune / Hair disorder

Often searched as: bald patches on head, sudden hair loss, round bald spots, hair falling out in clumps, losing hair in circles, bald spot appeared overnight, stress hair loss, alopecia photos…

Clinical urgency level

lowmediumhigh

Systems Affected

skinhair folliclesnails (in some cases)

Severity Levels

mild

One or few small patches of hair loss (<50% scalp affected), often self-resolving within months.

moderate

Multiple or expanding patches, persistent for over 6 months, affecting scalp and possibly beard/eyebrows.

severe

Alopecia totalis (complete scalp hair loss) or alopecia universalis (all body hair loss); associated with poorer prognosis for regrowth.

Red Flags

Rapid spread of hair loss patches over weeks
Loss of eyebrows, eyelashes, or beard in addition to scalp
Complete scalp hair loss (alopecia totalis)
Nail pitting, ridging, or dystrophy alongside hair loss
Hair loss in a child (may warrant earlier specialist evaluation)
Significant psychological distress affecting daily function

Clinical Presentation

Smooth, well-defined circular bald patch on the scalp — classic alopecia areata

Source: Wikimedia Commons (CC BY-SA 3.0)

Alopecia areata maligna — extensive multifocal patches

Source: Wikimedia Commons (CC BY-SA 3.0)

When to See a Doctor

Consult a dermatologist if you notice sudden, patchy hair loss, especially if patches are expanding or not regrowing within 2–3 months. Evaluation is also recommended to rule out other forms of alopecia (such as tinea capitis or scarring alopecia) and to assess for associated autoimmune conditions like thyroid disease.

Differential Diagnosis

Tinea capitis (fungal scalp infection — especially in children)
Trichotillomania (hair-pulling disorder)
Androgenetic alopecia (pattern baldness)
Traction alopecia
Discoid lupus erythematosus (scarring alopecia)
Secondary syphilis (moth-eaten alopecia)
Telogen effluvium (diffuse shedding)

Comorbidities

Thyroid disease (Hashimoto's, Graves')
Vitiligo
Atopic dermatitis
Type 1 diabetes
Rheumatoid arthritis
Down syndrome (higher prevalence)
Anxiety and depression

Prognosis

In mild cases (one or few small patches), spontaneous regrowth occurs in over 80% of patients within 1 year. However, recurrence is common. Extensive or long-standing disease, nail involvement, early onset in childhood, and personal/family history of atopy are associated with a worse prognosis. Alopecia totalis and universalis have lower rates of regrowth. New JAK inhibitor treatments (baricitinib, ritlecitinib) have significantly improved outcomes in severe cases.

Detailed Overview

Causes, Symptoms, and When to Take Action Alopecia areata is an autoimmune condition characterized by sudden hair loss, generally in round or oval patches. Though it primarily affects the scalp, it can involve any hair-bearing area. How It Looks Texture: The skin in bald patches is usually smooth and appears normal Color: The bald area typically matches the surrounding skin color Shape: Well-defined circular or oval patches of hair loss Location: Primarily on the scalp, beard area, or eyebrows; in more extensive forms, other body hair may be affected In many cases, hair loss is sudden and may be accompanied by "exclamation point" hairs (narrower at the base) or black dots (hairs broken off at the scalp level). Why Does It Appear? Caused by immune system attack on hair follicles, disrupting the normal hair cycle Genetic predisposition plays a role Environmental triggers (stress, infections) may initiate or exacerbate the condition Should You Be Concerned? While alopecia areata is not life-threatening, it can be distressing and sometimes persistent: Some cases resolve spontaneously within months In other cases, hair loss may be extensive (alopecia totalis or universalis) If patches multiply, enlarge, or do not improve over time, seeking specialist evaluation is recommended Can You Prevent It? There is no established way to prevent occurrence, as it is autoimmune in nature Awareness of triggers and early intervention upon first signs may improve outcomes 👉 How Piel AI Can Help Piel AI helps track the number, size, and appearance of alopecia patches over time via photos. Though not diagnostic, it aids in observing patterns of hair loss or regrowth to inform discussions with healthcare providers. Summary Alopecia areata is an autoimmune hair loss condition resulting in smooth, round patches. It is caused by immune attack on hair follicles, influenced by genetics and triggers. Some cases self-resolve; others may persist or recur. Monitoring, early evaluation, and support are key.

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