Freckles

Introduction

Freckles or ephelides are very common and first appear at about the age of 5 years as light‐brown pigmented macules on sun‐exposed areas of the skin of fair‐skinned individuals. Freckles appear or darken during periods of UV exposure. Freckling is significantly associated with certain polymorphisms of the melanocortin 1 receptor gene, the major freckle gene and is transmitted in an autosomal dominant fashion.

 

Pathophysiology

 

Exposure to UV radiation leads to overproduction of melanin by melanocytes, which is subsequently transferred to neighboring keratinocytes. Freckles could be considered a hyperactive response of melanocytes to UV radiation in predisposed individuals.

 

Pathology

 

There is no increase in the number of melanocytes in the pigmented macules but their melanosomes are long and rod-shaped, like those found generally in dark-skinned people. They form melanin more rapidly after exposure to sunlight than do those in the surrounding pale skin. With the light microscope, the only abnormality detectable is an increase in the quantity of melanin in the epidermis.

 

Environmental factors

 

UV exposure is responsible for the exacerbated pigment production by melanocytes that results in the development of freckles.

 

Clinical features

 

Freckles typically appear after excessive sun exposure (either chronic or intermittent) in fair‐haired individuals. They present as round or oval hyper pigmented macules with ill‐defined borders, usually measuring 2–4 mm in size. They are most numerous on the face, upper back, and dorsal forearms and hands. They increase in number, size and depth of pigmentation during the summer months and are smaller, lighter and fewer in number in the winter or even disappear. They may be cosmetically disfiguring.

 

 

Differential diagnosis

 

Freckles and solar lentigines are generally viewed as a response to sun exposure – solar lentigines to a greater extent – and both confer an increased risk for melanoma and epithelial skin cancers. They are distinguished from each other by the fact that lentigines persist even without UV exposure, and tend to appear more frequently in older ages. In addition, lentigines are histologically characterized by an increased number of epidermal melanocytes.

 

Disease course and prognosis

 

Freckles are benign lesions and often fade with age.

 

Treatment

 

No treatment is required. Application of 2–4% hydroquinone with a UVA-blocking sunscreen in the morning and retinoic acid in the evening produces significant lightening in most freckles. Alternatively, they are amenable to removal by laser or chemical peels.