Ephelides or freckles are small brownish lesions that are found on areas of photo exposition, principally on light colored skins and that of redheads and change when exposed to solar light. Histologically it is a hyper-pigmentation of the basal layer of the skin without an increase of melanocytes.
Dr. Thomas Fitzpatrick (1919-2003) was responsible for classifying skin depending in its capacity for assimilating solar radiation. It was in 1975 when this specialist, head of dermatology units at Harvard Medical ´school and the Massachusetts General Hospital divided human skin into six categories. Today these categories are universally accepted.
To set up this distinction, Fitzpatrick took into account skin shade, hair and eye color, if ephelides or freckles appeared, and the response of the skin to direct sunlight. In technical terms a larger phototype number indicates that our skin generates melanin more easily and in greater amounts.
There are six human phototypes and the corresponding solar protection factor (SPF) recommended to protect our skin from the sun’s ultraviolet radiation.
- Phototype I: Associated with persons of Celtic origin. Pale skin, that almost always burns instead of tanning, frequently suffers peeling or other photo-allergic reactions to prolonged sun exposure, usually has a large amount of freckles; normally platinum blond or red hair, blue or green eyes. SPF 65
- Phototype II: This skin type is associated with Caucasian persons. White skin, sensitive and delicate, typical of persons with blond or light color hair and blue or green eyes. They burn easily and almost never get tan and have the same solar reactions as those belonging to Phototype I. They also have many freckles. SPF: 35-45.
- Phototype III: It comprises mixed Caucasian types. Intermediate skin color, from clear to matte, typical of persons having brown hair and light-colored eyes. In the sun, their epidermis first reddens and, at times burns, then tans. It is the most common of the six. There can be some freckles. SPF: 30-40.
- Phototype IV: It belongs to people of Mediterranean type. Matte or dark skins, brown or black hair and brown eyes. The skin tans quickly and deeply, never burns and does not have freckles. SPF 20-25.
- Phototype V: It is typical of Hispanic and Native American types and pertains to those with darker skin than that of phototype IV. This type never burns, always tans to a dark color and has no freckles. SPF 15.
- Phototype VI: Pertains to persons of African descent, black skin than never burns and a total absence of freckles. Even if it does not seems so, these individuals are not born with guaranteed protection against skin lesions caused by the sun, although it is a lesser risk and their tolerance to sunburn is higher. SPF 4-10.
Gene or region studied