Table of Contents
Overview – Benign Pigmented Lesions
Benign pigmented lesions are melanocytic proliferations commonly observed in dermatology. While most are harmless, distinguishing them from melanoma is essential for safe and effective care. This article outlines the clinical features, natural history, and management of benign pigmented lesions including congenital and acquired melanocytic nevi, dysplastic nevi, freckles (ephelides), and solar lentigines. Medical students should be able to recognise and monitor these lesions appropriately and identify red flags for malignancy.
Congenital Melanocytic Nevi (Birthmarks)
Aetiology
- Present from birth; congenital in origin
Pathophysiology
- Caused by dermal and/or epidermal clusters of nevomelanocytes
Clinical Features
- Well-demarcated, pigmented papule or plaque
- May have overlying hair
- Sometimes surrounded by satellite nevi
- Rarely undergo malignant transformation
Management
- Baseline photograph and regular monitoring
- Excision if lesion changes in shape, colour, or size, or if suspicious
Acquired Melanocytic Nevi (Common Moles)
Aetiology
- Induced by UV exposure
- Often have a familial component
Epidemiology
- Common and normal in all skin types
Pathophysiology
- Benign proliferation of melanocytes at different skin layers
Clinical Features
- Round, well-defined pigmented macules
- Uniform colour and <1.5 cm in diameter
Stages of Development
- Junctional Nevus:
- Flat, symmetrical, pigmented macule
- Melanocytes located at dermoepidermal junction
- Compound Nevus:
- Slightly raised, dome-shaped lesion
- Melanocytes in epidermis and dermis
- Dermal Nevus:
- Fully raised papule/nodule
- Melanocytes located exclusively in the dermis
Management
- Monitor for changes in symmetry, colour, size, or borders
- Excisional biopsy if evolving or suspicious
Atypical Nevus (Dysplastic Nevus)
Aetiology
- UV exposure and progression from existing mole
Epidemiology
- Associated with:
- Family history
- High mole count
Pathophysiology
- Dysplastic melanocytes at the dermoepidermal junction
- Considered an intermediate lesion between benign naevi and melanoma
Clinical Features
- Mixed macular and papular lesion
- Central darker pigmentation
- Uneven colour, but fairly regular border and symmetry
Management
- Baseline photography
- Monitor regularly
- Excisional biopsy if evolving or concerning
Ephelides (Freckles)
Aetiology
- Triggered by sun exposure
Epidemiology
- Common in fair-skinned individuals (Fitzpatrick I–II)
- Often appear in childhood
Pathophysiology
- UV-induced increase in melanin (not melanocyte number)
- Located in basal layer keratinocytes
Clinical Features
- Small (<5 mm), light brown macules
- Found on sun-exposed skin
- May fade with sun avoidance
Management
- Sun protection: sunscreen, protective clothing, limited UV exposure
Solar Lentigo (Liver Spots)
Aetiology
- Chronic UV exposure
Epidemiology
- Common in middle-aged and elderly fair-skinned individuals
Pathophysiology
- Benign melanocytic proliferation at dermal-epidermal junction
Clinical Features
- Brown macules with well-defined borders
- Found on sun-exposed areas (face, hands, forearms)
- Typically 1–3 cm in diameter
Management
- Cosmetic removal options:
- Laser therapy
- Shave excision
- Cryotherapy
Summary – Benign Pigmented Lesions
Benign pigmented lesions such as melanocytic nevi, freckles, and solar lentigines are common and usually harmless. However, identifying atypical features and monitoring for change is crucial for early melanoma detection. Final-year students should be confident in assessing the evolution of benign pigmented lesions and knowing when to refer. For a broader context, see our Skin & Dermatology Overview page.