Causes of Acne on Arms and Trunk
Acne vulgaris on the arms and trunk is primarily caused by inflammation of the pilosebaceous unit due to excess sebum production, follicular hyperkeratinization, bacterial colonization, and inflammatory processes.1, 2
Pathophysiology of Truncal and Arm Acne
Primary Factors
- Acne vulgaris is a chronic inflammatory skin disease affecting the pilosebaceous unit (hair follicle and sebaceous gland) that can appear on both the face and trunk 1
- The pilosebaceous units on the trunk and arms contain sebaceous glands that can become inflamed, leading to acne formation 1
- Truncal acne follows the same pathophysiological mechanisms as facial acne but may present differently due to skin thickness and sebaceous gland distribution 2
Key Contributing Factors
- Excess sebum production - Hormonal influences stimulate sebaceous glands to produce more oil 1
- Follicular hyperkeratinization - Abnormal shedding of skin cells leads to plugging of hair follicles 2
- Bacterial colonization - Cutibacterium acnes (formerly Propionibacterium acnes) proliferates in the blocked follicles 3
- Inflammation - Immune response to bacterial presence and follicular rupture 2
Specific Causes for Trunk and Arm Acne
Environmental and Behavioral Factors
- Friction and occlusion - Tight clothing, backpacks, or sports equipment can trap sweat and oils against the skin 1
- Excessive washing with hot water - Can irritate skin and worsen acne on arms and trunk 1
- Skin irritants - Exposure to solvents, disinfectants, or over-the-counter anti-acne medications can exacerbate acne 1
- Sun exposure - Excessive sun exposure can worsen acne on exposed areas of the trunk and arms 1
Medical and Medication-Related Causes
- Hormonal factors - Androgen fluctuations affect sebum production on both face and trunk 2
- Medication side effects - Certain medications like anticancer agents (EGFR inhibitors, MEK inhibitors) can cause acneiform eruptions on the trunk and arms 1
- Genetic predisposition - Family history plays a role in determining susceptibility to truncal acne 2
Differences Between Facial and Truncal Acne
- Trunk and arm skin is thicker with larger sebaceous glands compared to facial skin 2
- Truncal acne may be more nodular or cystic in nature due to deeper pilosebaceous units 4
- Healing and resolution may take longer on the trunk and arms due to skin thickness 2
Prevention Strategies
- Avoid frequent washing with hot water 1
- Avoid skin irritants such as harsh soaps or anti-acne products not prescribed by a dermatologist 1
- Use alcohol-free moisturizing creams containing 5-10% urea 1
- Apply sunscreen (SPF 15 or higher) to exposed areas of the body 1
- Wear loose-fitting, breathable clothing to reduce friction and occlusion 1
Treatment Considerations
- Treatment approaches for truncal acne are similar to facial acne but may require more aggressive therapy due to skin thickness 4
- Topical treatments including benzoyl peroxide, retinoids, and antibiotics are first-line for mild to moderate truncal acne 1, 5
- For severe nodular acne on the trunk, oral medications including antibiotics or isotretinoin may be necessary 4
- Combined topical therapies targeting multiple pathogenic factors often yield better results for truncal acne 6
Understanding the causes of acne on the arms and trunk is essential for developing effective treatment strategies and preventing recurrence of this common skin condition.