Lentigo - Causes, Symptoms and Treatment

Definition

A lentigo is a small, sharply circumscribed, pigmented macule surrounded by normal-appearing skin. Histological findings may include hyperplasia of the epidermis and increased pigmentation of the basal layer. They may occur anywhere on the body and vary in color from tan-brown to black. Viewed under the microscope a lentigo shows an increased number of normal melanocytes. Although lentigo may be part of a genetic disorder, for the most part they are just isolated and unimportant spots. Lentigo are most frequently seen in adults over thirty, and they occur most commonly on sun exposed skin, face, back of hands, arms, chest and lower legs. They are typically tan or brown in color, and are generally flat. Lentigo maligna is mostly seen in patients 50 to 80 years old and accounts for ten to 15 percent of skin cancer cases.

Causes

1. Lentigo is caused by chronic sun exposure. This is one of the most common causes of lentigo.
2. Age may be another cause for lentigo. Older individuals have more cumulative sun exposure therefore is more likely to have lentigo.
3. The presence of large or numerous nevi (a type of birth mark) can cause lentigo maligna.
4. Irrespective of skin color, it is the uneven distribution of the melanin pigment in the skin that results in freckling. A freckle is nothing more than an unusually heavy deposit of melanin at one spot in the skin.

Symptoms

1. Lentigo maligna most commonly affects the sun-exposed skin of the head and neck, with a predilection for the nose and cheek.
2. The symptom is the appearance of darkened spots on the skin. They do not itch and are not painful.
3. The trouble spot is usually larger than 6 mm in diameter i.e. about the size of a pencil eraser.
4. These tend to be darker than the usual freckle and which do not fade in the winter.
5. Usually appears as a flat or mildly elevated mottled tan, brown or dark brown discoloration.

Treatment

1. Cryosurgery is a simple treatment for isolated lentigo. This procedure is often successful because of the susceptibility of melanocytes to freezing with liquid nitrogen. Squamous cells resist injury at -20°C, whereas melanocytes freeze at -4 to -7°C.
2. Noninvasive topical creams are also used. After several months of application, tretinoin cream and hydroquinone cream can lighten lentigo.
3. However radiation therapy can be used. But it is not a first line therapy and probably has its best use as an adjuvant therapy when the disease reaches in severe condition.
4. Biotherapy can also used to treat lentigo. It is based on modern molecular biology, immunology and genetics. Biological therapy works either directly against the spots or indirectly to change the way the patient's body reacts to a spot.
5. If lentigo reoccurs or come after treatment then some sunscreen can be used.
6. Topical treatment with agents such as azelaic acid may be used but they do not completely remove the spots on the skin.