What causes alopecia (hair loss) around the mouth in a patient?

Facial Alopecia Around the Mouth: Causes and Diagnostic Approach

Alopecia areata is the most common cause of patchy hair loss around the mouth, representing an autoimmune condition where T lymphocytes attack hair follicles, resulting in non-scarring hair loss that can affect any hair-bearing area including facial hair. 1, 2

Primary Causes to Consider

Autoimmune Etiology

• Alopecia areata is the leading diagnosis for facial hair loss, with approximately 20% of patients having a family history indicating genetic susceptibility 1, 2
• The condition associates with other autoimmune diseases including thyroid disease, lupus, and vitiligo, supporting its autoimmune pathogenesis 1, 2
• Neurogenic inflammation may contribute to hair follicle damage by triggering mast cell activation and keratinocyte apoptosis 3

Infectious Causes

• Tinea barbae (fungal infection of the beard area) causes patchy hair loss with scalp inflammation and scaling, requiring fungal culture for definitive diagnosis 1, 2
• Dental infections may trigger alopecia areata through shared immune mediators, making oral cavity examination essential in unexplained cases 4

Behavioral and Mechanical

• Trichotillomania (compulsive hair pulling) can mimic alopecia areata but shows incomplete hair loss with firmly anchored broken hairs that remain in anagen phase 1, 2
• The key distinction is that trichotillomania shows broken hairs firmly anchored in the scalp, unlike the exclamation mark hairs of alopecia areata 5

Systemic Diseases

• Systemic lupus erythematosus can cause both scarring and non-scarring facial alopecia 1, 2
• Secondary syphilis presents with patchy "moth-eaten" hair loss pattern 1, 2

Diagnostic Approach

Clinical Examination

• Look for exclamation mark hairs (short broken hairs around expanding patches), which are pathognomonic for alopecia areata 1, 2
• Check for nail changes including pitting, ridging, or dystrophy, present in approximately 10% of alopecia areata patients 1
• Perform oral cavity examination to identify potential dental infections as triggering foci 4

Dermoscopy (First-Line Diagnostic Tool)

• Dermoscopy is the single most useful non-invasive tool to differentiate alopecia areata from other conditions 1, 5
• Look for yellow dots (present in 6-100% of alopecia areata cases), which indicate active disease when regularly round 5
• Identify exclamation mark hairs and cadaverized hairs as characteristic features 1, 5
• Black dots appear in 0-84% of cases 5

Laboratory Testing (When Diagnosis is Uncertain)

• Fungal culture is mandatory when tinea barbae is suspected, as clinical diagnosis alone leads to treatment failure 1, 2
• Vitamin D levels: 70% of alopecia areata patients have deficiency (<20 ng/mL) versus 25% of controls, with lower levels correlating inversely with disease severity 1, 2
• Serum zinc levels tend to be lower in alopecia areata patients, particularly those with resistant disease >6 months duration 1
• TSH and thyroid antibodies to screen for associated autoimmune thyroid disease 1
• Serology for lupus and syphilis when systemic disease is suspected 1, 2

Skin Biopsy (When Needed)

• Indicated when diagnosis remains uncertain after dermoscopy or when scarring alopecia is suspected 1, 2
• Helps differentiate primary scarring alopecias (discoid lupus, lichen planopilaris) from non-scarring conditions 6, 7, 8

Common Pitfalls to Avoid

• Do not order excessive laboratory tests when characteristic dermoscopic features (yellow dots, exclamation mark hairs) clearly establish the diagnosis of alopecia areata 1
• Do not confuse trichotillomania with alopecia areata: trichotillomania shows incomplete hair loss with firmly anchored broken hairs, while alopecia areata shows exclamation mark hairs 1, 5
• Do not overlook the psychological impact of facial alopecia, which causes considerable psychological and social disability warranting assessment for anxiety and depression 1, 2
• Do not forget that 34-50% of alopecia areata cases recover spontaneously within one year, making observation reasonable for limited disease 1

Prognostic Factors

• Disease severity at presentation is the strongest predictor: patients with <25% hair loss have 68% chance of being disease-free at follow-up versus only 8% for those with >50% initial hair loss 5
• Childhood onset and ophiasis pattern (scalp margin involvement) carry poorer prognoses 1, 2

Note on Medication-Induced Alopecia

• Corticosteroids themselves can paradoxically cause alopecia as an adverse effect, along with hirsutism and thinning scalp hair 9