Brown Spots on Back and Shoulders: Causes, Evaluation, and Treatment

Flat, brown macules on the back and shoulders are common and usually benign. Accurate diagnosis guides appropriate management.

Common Causes

1. Solar Lentigines (Age/Liver Spots)

Caused by cumulative UV exposure. Sharply demarcated, light to dark brown, 2–20 mm. Increase with age. Benign but indicate photodamage.

2. Post-Inflammatory Hyperpigmentation (PIH)

Follows inflammatory skin conditions (acne, eczema, psoriasis, insect bites). More common in darker skin types. Fades slowly over months to years.

3. Melasma

Hormonally influenced (pregnancy, OCPs), but can appear on shoulders with sun exposure. Symmetric, irregular borders. Worsens with UV.

4. Café-au-Lait Macules

Light brown, well-circumscribed, present from childhood. ≥6 spots >5 mm (prepubertal) or >15 mm (adult) suggests neurofibromatosis type 1.

5. Congenital Melanocytic Nevi

Present at birth or early infancy. Vary in size; giant (>20 cm) carry melanoma risk.

6. Drug-Induced Hyperpigmentation

Medications: amiodarone, antimalarials, tetracyclines, NSAIDs, chemotherapeutics.

When to See a Dermatologist

• New or changing lesion (ABCDE: Asymmetry, Border irregularity, Color variation, Diameter >6 mm, Evolution)
• Itching, bleeding, crusting
• Rapid growth or darkening
• Multiple café-au-lait spots
• Uncertain diagnosis

Treatment Options

• Topical: Hydroquinone, retinoids, azelaic acid, vitamin C, niacinamide, cysteamine.
• Procedural: Intense pulsed light (IPL), Q-switched lasers (Nd:YAG, alexandrite), fractional lasers, chemical peels, cryotherapy.
• Prevention: Daily broad-spectrum SPF 30+ is essential to prevent recurrence and new lesions.

Always confirm diagnosis before treatment; melanoma can mimic benign pigmented lesions.