Types of Lentigo

1. Lentigo simplex 

This is the most common type of lentigo. It arises during childhood or early adult life. Moreover, it may disappear without treatment. Lentigo simplex occurs on the trunk area, arms and legs. This type of lentigo tends to have a dry surface. Lentigo simplex could also be a precursor to junctional nevus, a type of mole.

2. Solar lentigo 

A solar lentigo is caused by exposure to the sun's rays. It commonly occurs in people above 40. In fact, solar lentigines are common on sun-exposed areas. For instance, the face, shoulders, arms, hands, and lower legs. The sun's radiation causes the pigment cells or melanocytes in the skin to multiply. Thus, this leads to these dark pigmented lesions.

Solar lentigines have a moth-eaten outline. In fact, they may slowly enlarge in size. Solar lentigines are also known as liver spots or age spots. They may be a precursor to seborrheic keratosis, a non-cancerous, wart-like skin condition.

3. Inkspot lentigo 

Inkspot lentigo, or reticulated lentigo, occurs following a sunburn in fair-skinned individuals. Moreover, it appears as a dark brown to black irregular ink spot-like macule.

4. PUVA lentigo 

PUVA lentigo generally occurs after psoralen and ultraviolet A (PUVA) therapy. It appears on areas that have received the therapy.

5. Tanning bed lentigo

This type of lentigo occurs on areas exposed to indoor tanning beds.

6. Radiation lentigo

This type of lentigo is seen in sites exposed to accidental or therapeutic radiation. It often occurs in late-stage radiation, dermatitis as seen in epidermal atrophy and subcutaneous fibrosis.

7. Mucosal lentigo

Mucosal lentigo is a melanotic macule occurring on mucosal surfaces like the lip, vulva, penis and anus.

8. Generalized lentigines

Generalized lentigines or lentigines profusa are present on several sites of the body from early childhood. This is not associated with any syndrome.

9. Agminated lentigines

This is a rare pigment disorder. There are multiple lentigines in this case. Moreover, these have sharp demarcations in the midline. Agminated lentigines are usually associated with neurological and developmental abnormalities.

10. Patterned lentigines

Patterned lentigines are commonly observed in the certain populations. These lentigines occur in a pattern, on the face, lips, buttocks, palms, and soles.

11. Lentiginosis syndromes

While lentigines may occur independently, they may occur as part of different syndromes as well. These syndromes are usually genetic, and present at birth or arise in early childhood. Some of the syndromes that may cause lentigines are Cowden syndrome, Peutz-Jeghers syndrome, Noonan syndrome, Laugier-Hunziker, Moynahan, Xeroderma pigmentosum, Myxoma syndromes, Ruvalcaba-Myhre-Smith, and Bannayan-Zonnana syndrome.

Lentigines that exhibit the following symptoms may be malignant due to the following reasons:

• Asymmetrical in shape
• Uneven borders
• Uneven pigmentation
• Have diameters exceeding 6mm
• Are convex and rough to touch
• Itch
• Inflamed

If any of these symptoms or early melanoma appear, visit a dermatologist or oncologist immediately.

Treatments of Lentigo

Benign lentigines do not pose a health risk. However, their cosmetic appearance may improve with different topical applications and medical procedures. The doctor will assess the cause, type and nature of the lentigines before recommending a treatment.

Benign lentigo

Topical applications lighten benign lentigines. For example, some of the topical applications are SPF 50+ broad-spectrum sunscreen, hydroquinone bleaching cream, alpha hydroxy acids, lotions and creams with vitamin C, and retinoids.

1. Tretinoin cream and hydroquinone cream: These noninvasive topical creams can lighten lentigines after several months of application.
2. Cryosurgery: This treatment is often combined with ablative therapy to freeze melanocytes with liquid nitrogen. In fact, this is the most suitable treatment for isolated lentigines.
3. Laser treatment: Short-pulsed, pigment-specific lasers can be used to selectively destroy the pigment within the lentigo. 

Malignant lentigo 

If there are any indications that the lentigines are malignant, the following treatments may be used:

1. Surgery 
2. Perfusion 
3. Chemotherapy
4. Radiation therapy

In conclusion, it is important to consult an oncologist for malignant lentigo.