Two patterns of solar lentigines: A histopathological analysis of 40 Japanese women

Abstract

Solar lentigines are common acquired pigmented lesions on sun-exposed skin. Their histopathological features have been reported as large numbers of melanocytes at the base of clubbed and budding rete ridges. In this study, biopsies were taken from facial solar lentigines in 40 Japanese women, and the sections were stained using hematoxylin-eosin, Fontana-Masson, and immunostained for melanocytes and Langerhans cells in order to verify the histological patterns of Japanese patients. We characterized the histopathological features of solar lentigines on the face and identified two patterns: one pattern (20/40 cases) demonstrated a flattened epidermis with basal melanosis, and the other pattern (20/40 cases) showed epidermal hyperplasia with elongated rete ridges composed of deeply pigmented basaloid cells. We termed the former pattern the "flattened epidermis" group, and the latter the "budding" group, respectively. The flattened epidermis group showed a significantly thinner epidermis, more severe solar elastosis and fewer Langerhans cells in the epidermis as compared with the budding group. We concluded that more severely sun-damaged solar lentigines might show the changes observed in the flattened epidermis group. Langerhans cells in the epidermis of solar lentigines might play a role in the remission of postinflammatory pigmentation due to aesthetic treatment.

Characteristics of keratinocytes in facial solar lentigo with flattened rete ridges: comparison with melasma

“…Nonetheless, flattened rete ridges are a frequent finding in SL, and tend to occur more often on the face compared with other anatomical sites. In an earlier report, more than half of cases of facial SL showed flattening rather than elongation of rete ridges. In a more recent study carried out in Japanese patients, more severe solar elastosis and fewer Langerhans cells were seen in the epidermis in the 20 cases (out of 40) that showed flattened rete ridges, compared with the budding (elongated) group .…”

“…In an earlier report, more than half of cases of facial SL showed flattening rather than elongation of rete ridges. In a more recent study carried out in Japanese patients, more severe solar elastosis and fewer Langerhans cells were seen in the epidermis in the 20 cases (out of 40) that showed flattened rete ridges, compared with the budding (elongated) group . The authors suggested that more severely sun‐damaged solar lentigines might show the changes observed in the flattened rete ridge group.…”

“…Solar lentigo (SL) is a common acquired hyperpigmentary disorder, frequently occurring on the face. The most histologically distinguishable features that differentiate SL from other pigmentary disorders are the increase in the number of melanocytes and in content of melanin in the lower epidermis, and the downward elongation of rete ridges . Nonetheless, flattened rete ridges are a frequent finding in SL, and tend to occur more often on the face compared with other anatomical sites.…”

“…The most histologically distinguishable features that differentiate SL from other pigmentary disorders are the increase in the number of melanocytes and in content of melanin in the lower epidermis, and the downward elongation of rete ridges. 1,2 Nonetheless, flattened rete ridges are a frequent finding in SL, and tend to occur more often on the face compared with other anatomical sites. In an earlier report, 2 more than half of cases of facial SL showed flattening rather than elongation of rete ridges.…”

Protection against summer solar lentigo over‐pigmentation with a SPF30 daily cream

“…The lentigines have been widely investigated histologically, the main characteristics being epidermal hyperplasia, a budding of the rete ridges, and hyperpigmentation …”