Physical Examination Characteristics of Solar Lentigines
Solar lentigines present as well-demarcated, brown to dark brown macules on chronically sun-exposed skin, most commonly on the face, dorsal hands, forearms, and upper back in fair-skinned individuals. 1
Clinical Appearance
- Color and morphology: Uniformly pigmented, light to dark brown macules with sharply defined borders 2, 3
- Size: Typically range from a few millimeters to 1-2 centimeters in diameter 2
- Texture: Flat (macular) with smooth surface; no palpable elevation 2, 3
- Distribution: Scattered or confluent lesions on chronically photoexposed areas including face, dorsal hands, forearms, shoulders, and upper back 1, 2
Key Distinguishing Features on Examination
- Regular borders: Unlike melanoma, solar lentigines have uniform, well-circumscribed edges without notching or irregularity 2
- Homogeneous pigmentation: Even color distribution throughout the lesion without variegation 2, 3
- Background skin changes: Typically occur in context of other photoaging signs including solar elastosis, telangiectasias, and actinic keratoses 1, 3
Dermoscopic Features (When Available)
- Regular honeycomb pattern: Uniform pigment network at the dermoepidermal junction 4
- Edged dermal papillae: Well-defined papillary structures visible on confocal microscopy 4
- Cord-like rete ridges: Regular epidermal architecture at the dermoepidermal junction 4
Associated Findings
- Patient demographics: Predominantly middle-aged to elderly patients with fair skin (Fitzpatrick types I-III) and history of chronic sun exposure 1, 2
- Concurrent lesions: Often accompanied by actinic keratoses, PUVA lentigines (in patients with prior phototherapy), and other signs of photodamage 1
- Multiple lesions: Rarely solitary; presence of one lesion indicates chronic UV exposure and predicts development of additional lesions 1
Clinical Pitfalls to Avoid
- Do not confuse with lentigo maligna: Solar lentigines lack asymmetry, border irregularity, color variegation, and diameter >6mm that characterize melanoma 5, 2
- Distinguish from seborrheic keratoses: Solar lentigines are flat macules without the "stuck-on" appearance or verrucous texture of seborrheic keratoses 2
- Recognize PUVA lentigines: In patients with history of psoralen plus UVA therapy, lentigines may be more numerous, darker, and occur in both sun-exposed and sun-protected areas 1