27/02/2026
✅ Becker’s Nevus (Becker Melanosis)
2. “Beyond textbooks—real cases, real insights. Sharpen your clinical eye. ”
📍 What it is
A benign cutaneous hamartoma characterized by:
Localized hyperpigmentation
Hypertrichosis
Gradual enlargement
Androgen sensitivity
It is not a true melanocytic nevus — rather an epidermal–pilosebaceous hamartoma.
⏳ When does it appear
Typical timeline
Rarely obvious at birth
Usually appears around puberty (10–20 yrs)
Gradually enlarges over months to years
Becomes darker and hairier with androgen influence
👉 Many patients say “birthmark” because early faint pigmentation existed, but the real expression occurs in adolescence.
⚙️ How does it develop (Pathogenesis)
1. Androgen receptor hypersensitivity
This is the key concept.
Lesional skin shows:
Increased androgen receptors
Increased hair follicles
Sebaceous gland hypertrophy
Hence: ✔ Male predominance
✔ Pubertal onset
✔ Hypertrichosis
✔ Acne sometimes over lesion
👨⚕️ Epidemiology
Male : female ≈ 5:1
Usually unilateral
Common sites:
Shoulder
Chest
Scapular region
Upper arm
Occasionally abdomen/flank (like your case)
🔬 Clinical Features
Early stage
Light brown patch
Irregular borders
No hair initially
Mature stage
Darker pigmentation
Coarse hair growth
Slight thickening
Gradual enlargement
Lesion stabilizes after a few years.
👉 Hamartoma = a focal overgrowth of mature normal tissue native to that site, arranged in a disorganized way.
So:
Tissue is normal in type
But excessive and architecturally abnormal
It is a developmental malformation, not a true tumour.
🧠 Breaking the Word
Hamartia (Greek) → error
Oma → mass
👉 Meaning: “an error in tissue development forming a mass.”