Lentigo simplex, Lentigo solaris

Lentigo juvenilis, lentigo benigna, lenticular stain, nevoid lentigo, naevus incipiens, lentigo of the mucous membrane, mucosal lentigo.

Cutaneous or mucous, acquired melanocyte hyperplasia, which appears as hyperpigmentation. It is UV-induced. There is no preference for light-exposed areas. The hyperpigmentation does not fade in winter.

• Mostly occurring in the first years of life

• In principle, however, lentigo simplex can occur at any age

• Mostly phased progression

• Lentigo simplex -> naevoid lentigo -> melanocytic naevus (junctional naevus to melanocytic naevus of the dermal type)

• UV-induced lentigines can develop at any age

  • At an older age, the phased development decreases

• People with skin type I according to Fitzpatrick and patients with peripheral neurofibromatosis or Peutz-Jeghers syndrome are less likely to develop the phased progression. 

  • This is the reason why redheads are prone to lentigines

• Brownish, usually multiple, up to approx. 5 mm (but also larger up to 3.0 cm) in diameter, sharply defined hyperpigmentation with irregular pigmentation.

• If lentigines occur in large numbers, they are referred to as lentiginosis.

• Special form 

  • Ink spot lentigo or reticular lentigo 

    • Black, sometimes bizarrely shaped reticular lentigo often occurring after intensive UV exposure in the shoulder girdle area.

Avoid common mistakes:

• Lentigines which occur mainly in red-haired children, are called ephelides

• If perioral lentiginosis occurs, a gastroenterological presentation must be made to rule out Peutz-Jeghers syndrome

• Clinic
• Biopsy if necessary

• Irregular, often club-shaped, retracted epidermal rete cones

• Basal hyperpigmentation with increased number of individual melanocytes in the basal layer

• Single dermal localised melanophages

• No melanocyte nests

• No solar elastosis

Rare transitions to malignant melanoma possible.

Sunscreen.

Often transition into a junctional nevus.

1. Samuelov, L., et al, Extensive lentigo simplex, linear epidermolytic naevus and epidermolytic naevus comedonicus caused by a somatic mutation in KRT10. Br J Dermatol, 2015. 173(1): p. 293-6.
2. Hafner, C., et al, The absence of BRAF, FGFR3, and PIK3CA mutations differentiates lentigo simplex from melanocytic nevus and solar lentigo. J Invest Dermatol, 2009. 129(11): p. 2730-5.
3. Erkek, E., et al, Type I hereditary punctate keratoderma associated with widespread lentigo simplex and successfully treated with low-dose oral acitretin. Arch Dermatol, 2006. 142(8): p. 1076-7.
4. Awaya, A., K. Watanabe, and S. Kato, Individuals exhibiting conspicuous nevi (lentigo simplex) are resistant to allergic rhinitis/conjunctivitis (pollinosis), but those who do not show increased susceptibility to pollinosis. Microbiol Immunol, 2003. 47(1): p. 101-3.
5. McCarthy, D.J., Lentigo simplex. J Am Podiatr Med Assoc, 1987. 77(10): p. 539-43.
6. Horikoshi, T., K. Jimbow, and S. Sugiyama, Comparison of macromelanosomes and autophagic giant melanosome complexes in nevocellular nevi, lentigo simplex and malignant melanoma. J Cutan Pathol, 1982. 9(5): p. 329-39.
7. Hirone, T. and Y. Eryu, Ultrastructure of giant pigment granules in lentigo simplex. Acta Derm Venereol, 1978. 58(3): p. 223-9.