Difference Between Freckles and Lentigines
Core Distinction
Freckles (ephelides) are genetically determined, sun-induced pigmented macules that darken with sun exposure and fade in winter, whereas lentigines are permanent pigmented lesions caused by increased melanocyte number and sun damage that do not fade seasonally. 1, 2
Clinical Characteristics
Freckles (Ephelides)
- Small, light brown macules appearing exclusively on sun-exposed areas in fair-skinned individuals 1, 3
- Darken with ultraviolet exposure and fade during winter months 2
- Result from increased melanocyte activity without an increase in melanocyte number 1
- Genetically determined but require sun exposure for manifestation 2
Lentigines (Solar Lentigines)
- Permanent pigmented lesions induced by chronic sun exposure and photodamage 2, 3
- Do not fade with reduced sun exposure 2
- Show increased melanocyte number on histopathology, with moderate elongation of rete ridges and increased melanin from basal layer to stratum corneum 1
- Electron microscopy reveals increased melanocyte number and presence of giant melanin granules 1
Histopathological Differences
The fundamental pathologic distinction is that freckles show increased melanocyte activity without increased melanocyte number, while lentigines demonstrate both increased melanocyte number and architectural changes consistent with lentigo simplex. 1
- Freckles: Normal melanocyte count with enhanced melanin production 1
- Lentigines: Increased melanocyte density, elongated rete ridges, and mild inflammatory infiltrate with melanophages 1
Clinical Context in Pemphigus
In patients with pemphigus history, distinguishing these lesions is straightforward as neither condition is affected by pemphigus:
- Both represent benign pigmentary changes unrelated to autoimmune blistering disease 4
- Post-inflammatory hypopigmentation from pemphigus lesions differs from both freckles and lentigines by having a history of preceding blistering and inflammation 5
- Pemphigus patients may develop lentigines from chronic phototherapy (PUVA), which are dose-dependent and permanent 4
Treatment Implications
- Freckles may improve with sun avoidance and sunscreen use, as they are sun-induced and reversible 2, 3
- Lentigines require active intervention (laser therapy, cryotherapy, chemical peels) as they represent permanent structural changes 3, 6
- Frequency-doubled Nd:YAG (532 nm) laser effectively treats both conditions, though lentigines show no recurrence while freckles may partially recur (40% at 24 months) 6
Critical Diagnostic Pitfall
Do not confuse café-au-lait macules with either freckles or lentigines—café-au-lait patches are lentiginous patches with giant melanin granules that may indicate neurofibromatosis or Carney complex, requiring genetic evaluation. 4, 1, 7