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Latest update 14/12/09
Pathology
- A lentigo (syn. lentigine), unlike an freckle (ephilis) maintains its pigmentation throughout the year. The increase in melanin is often associated with an increase of normal melanocytes at the dermal-epidermal junction. There are 3 main types of lentigo:
Diagnosis: Simple lentigo (syn. lentigo simplex)
Key diagnostic features
- Large numbers of lentigines are very common, especially in patients with red hair
- Age - tend to arise in childhood and may increase in number in young adults
- Rarely, lesions may erupt suddenly or occur in vast numbers
- Distribution – can be found on any area of skin, mucosal surfaces and the conjunctiva
- Naked eye appearance - usually appear as small, sharply demarcated macules 3-5 mm in diameter displaying a uniform light / dark brown colour
- Dermoscopy - a symmetrical pattern with a typical pigment network that tends to end abruptly at the periphery (unlike in aquired melanocytic naevi where the pigment tends to fade significantly towards the edge)
- The majority of simple lentigines remain static or disappear in adult life
- They can be distinguished from freckles by their darker colour, wider distribution and the fact that they do not disappear in winter months. It may be very difficult however to distinguish lentigines from aquired melanocytic naevi on clinical grounds
Additional notes
- There are a small number of uncommon / rare conditions in which lentigines are associated with systemic pathology. Two such examples are:
- Peutz-Jeghers Syndrome – lesions on lips, buccal mucosa, fingers and toes in association with intestinal polyps
- Multiple Lentigines Syndrome (syn. LEOPARD syndrome) – this rare disorder is characterised by large numbers of lesion first starting at birth / early childhood, and is associated with cardiomyopathy, growth retardation and ocular disorders
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Figure 1 - Simple lentigo
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Figure 2 - Dermoscopic appearance of figure 1
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Figure 3 – Peutz-Jeghers Syndrome
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Diagnosis: Solar lentigo
Key diagnostic features
- Commonly known as age spots or liver spots
- Distribution - sun-induced lesions most prominant on the face, forearms and dorsal aspects of the hands
- Appearance - flat, uniformly brown and can be quite large
- Dermoscopic appearance - as with other lesions the appearance depends on the site. On the trunk and limbs they tend to have a 'moth-eaten' border and may have a parallel-like 'fingerprint' pattern. Lesion on the face are more complex (see below)
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Figure 1 – Large numbers of solar lentigines
This patient worked outdoors for many years without protection
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Figure 2 – Solar lentigo on cheek
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Figure 3 – Solar lentigo left mid forehead
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Figure 4 – Dermoscopic appearance of figure 3
The structure of facial skin differs from skin on other body sites -as a result dermoscopic appearances of melanocytic lesions on the face demonstrate different patterns to elsewhere
Note the well established pseudonetwork (arrows) that are found in solar lentigo on the face
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Figure 5 – Solar lentigo on cheek
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Figure 6 – Dermoscopic view of figure 5
The pseudo-network found in a solar lentigo takes on a different appearance to the pattern found in a lentigo maligna (see article on melanoma and lentigo maligna)
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Figure 7 – Solar lentigines on back of hands
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Figure 8 – Close up view of a solar lentigo on the forearm
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Figure 9 – Dermoscopic view of figure 8
A sharply demarcated ‘moth-eaten’ border
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Diagnosis: Ink-spot lentigo
Key diagnostic features
- A small (often < 5mm), dense black macule. The edge may be irregular
- Often solitary
Additional notes
- Dermoscopic examination reveals a thickened irregular network, the appearance is however monomorphic and this can help differentiate the lesion from an early melanoma. Where doubt exists the lesion should be excised with a clear 2mm margin and sent for urgent histological examination
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Figure 1 - Ink-spot lentigo on upper back
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Figure 2 – Dermoscopic view of figure 1
Ink-spot lentigo have a very monomorphous pigment network
The white lines in the upper left hand corner are artefact
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Figure 3 - Dermoscopic view of ink-spot lentigo
This solitary lesion was excised as the pigment network was less orderly. Histology confirmed the diagnosis of an ink-spot lentigo
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