Solar Lentigo (Actinic Lentigo)

Senile Lentigines

“sunburn freckles” (may overlap)

Reticulated lentigo (potentially related)

Ink spot lintigo (potentially related)

Epidemiology and Etiology:

• Increase in number with age
• Sun exposure is the eliciting factor

Common sites:

• Sun-exposed areas:
• Dorsa of the hands
• Face and extensor surfaces of the forearms

Gross features:

• Multiple lesions in areas exposed to the sun
• Not indurated
• Uniform dark brown colour
• Irregular outline (but not as much as lentigo maligna)
• Minute to > 1 cm and may coalesce

Histologic features:

• Rete ridges elongated (subtly or more significantly)
• No horn cysts (as in SK)
• Deeply pigmented basaloid cells intermingled with melanocytes
• slightly to significantly increased melanocytes
• Melanocytes arranged mostly as single cells
• Not in contiguity with one another
• Minimal cytologic atypia
• No pagetoid spread
• elastosis in upper dermis
• melanophages scattered in the upper dermis (often)

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Risk marker for development of melanoma
• Commonly numerous in the skin around melanomas, as seen in melanoma reexcision specimens

References:

• Elder DE (ed.) Lever’s Histopathology of the Skin, 10^th ed (2009)