Lentigines, Solar LentiginesDefinition: Lentigines are clearly defined, pigmented, flat or slightly raised lesions. Lentigines do not fade in the winter months. Solar Lentigines (SL) are also known as “liver” or “wisdom- spots”, are harmless areas of hyperpigmentation on the skin due to ultraviolet (UV) radiation.Etiology:  Lentigines can occur due to exposure to ionizing radiation. Familial syndromes associated with widespread lentigines originate from mutations in Ras-MAP kinase, mTOR signaling and PTEN pathways. SLs occur due to exposure to ultraviolet radiation, as seen in sun damage/ sunburn, indoor tanning and phototherapy. Exposure causes local proliferation of melanocytes and the accumulation of melanin within keratinocytes.Epidemiology: Lentigines affect males and females equally, and may occur in all ages and races. Lentigines are common in individuals with fair- skin, and frequently arise in sun- exposed areas on individuals with darker skin. Lentigines are commonly seen in individuals over 40 years of age. Signs: There are many classifications of lentigines depending on their appearance on the body, causative factors and likelihood of progressing to other diseases or conditions. These include lentigo simplex, ink spot lentigo, and tanning bed lentigo. SLs are flat, well- circumcised round, oval or irregularly shaped patches. They may be skin coloured, tan, dark- brown or black depending on skin tone. Sls range from a few millimeters to several centimeters in diameter. SLs may be scaly.Differentials: Actinic keratosis, Seboorhoeic keratosis, Melanoma, nMelasmaDiagnosis: Lentigines are diagnosed clinically by their appearance. Examination using dermatoscopy may be used to differentiate lentigines from melanoma. A diagnostic excisional skin biopsy may be performed for histological examination. Histopathology will show a thickened epidermis, increased melanocytes along the basal layer of the epidermis and increased melanin pigment within the keratinocytes.Treatment: Most lentigines persist indefinitely. SPF 50+ broad-spectrum sunscreen or hydroquinone bleaching cream may be used to lighten the lesions. Bleaching agents, however, are not effective in SL. Individual lesions may be lightened using cryotherapy, intense pulsed light or pigment lasers. Preventative measures include minimizing sun exposure and using sunscreen early in life. References:

Brown spots, lentigines and freckles. DermNet®. Published October 26, 2023. Accessed September 25, 2024. https://dermnetnz.org/topics/brown-spots-and-freckles#:~:text=Lentigines%20are%20common%20in%20peopleLentigo, lentigines | DermNet NZ. dermnetnz.org. https://dermnetnz.org/topics/lentigoChan B. Solar lentigo | DermNet NZ. dermnetnz.org. Published 2014. https://dermnetnz.org/topics/solar-lentigo