What causes sweat-related excoriations around the armpits?

Causes of Sweat-Related Excoriations Around the Armpits

Sweat dermatitis is the primary cause of sweat-related excoriations around the armpits, characterized by irritant inflammatory reactions due to prolonged exposure to retained sweat on the skin, which can lead to scratching and subsequent excoriations.

Primary Causes

Sweat Dermatitis

• A form of irritant inflammatory dermatosis commonly seen in hot and humid environments 1
• Characterized by:
  • Brownish "parchment-like" or "crinkled cellophane paper-like" patches
  • Areas of exfoliation and excoriation
  • Increased skin markings on dermoscopy
  • Prominent eccrine duct openings
  • Spongiotic dermatitis on histopathology 1

Contributing Factors

• Profuse sweating triggered by:
  • High heat index/hot climate
  • Friction from clothing
  • Prolonged activity in poorly ventilated spaces
  • Overcrowding
  • Physical activities that increase sweating 1, 2

Secondary Causes and Complications

Hyperhidrosis

• Excessive sweating beyond what's needed for normal thermoregulation
• Affects approximately 3.12% of the US population
• Creates conditions that promote skin irritation and subsequent excoriation 3

Excoriation Disorder

• Psychiatric condition characterized by recurrent skin picking
• Lifetime prevalence of 3-5% in the general population
• More common in females
• Chronic course with periods of exacerbation
• Patients are aware of self-destructive behavior but unable to stop 4, 5

Other Dermatological Conditions

• Atopic dermatitis with axillary involvement can lead to excoriations
• Characterized by erythema, edema, xerosis, and lichenification 6
• Pruritus (itching) is a hallmark that leads to scratching and excoriation

Urticaria

• Can present with weals and intense pruritus
• Physical urticarias can be triggered by heat, sweat, or pressure
• Cholinergic urticaria specifically triggered by sweating 6

Diagnostic Features

Clinical Presentation

• Brownish patches with areas of exfoliation
• Excoriations from scratching
• Increased transepidermal water loss (TEWL) in affected areas (found in 88% of patients) 1

Dermoscopic Findings

• Increased skin markings
• Deep brown pigmentary changes
• Whitish scales
• Islands of eroded skin
• Prominent eccrine duct openings 1

Management Approach

Prevention Strategies

• Avoid triggers:
  • Extreme temperatures
  • Prolonged exposure to hot environments
  • Tight or occlusive clothing
  • Prolonged physical activities in hot weather without breaks 6

Treatment Options

• Regular bathing with warm water followed by moisturizers 6
• Use of neutral pH, fragrance-free hypoallergenic soaps or non-soap cleansers 6
• Topical treatments to reduce inflammation and pruritus
• For psychiatric components like excoriation disorder, consider:
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Mirtazapine for cases with significant pruritus 5

Common Pitfalls and Caveats

1. Misdiagnosis: Sweat dermatitis is often misdiagnosed or unrecognized due to lack of awareness 1

2. Overlooking psychiatric components: Excoriation disorder may be overlooked as a contributing factor to skin lesions 4

3. Inappropriate soap use: Using alkaline soaps can worsen the condition by disrupting skin barrier function 6

4. Neglecting environmental factors: Failing to address environmental triggers can lead to persistent symptoms

5. Delayed treatment: Prolonged inflammation can lead to secondary changes including lichenification and hyperpigmentation

By addressing both the physical and potential psychological aspects of sweat-related excoriations around the armpits, clinicians can provide comprehensive care that addresses the root causes of this condition.