Diagnostic Atlas of Melanocytic Pathology.pdf

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SEction 1
Ephelides and lentigo
Ephelides
lentigo simplex
PUVA, sunbed and radiation lentigines
Genital melanosis and lentigines
Acral lentigo
Solar lentigo (actinic lentigo, lentigo senilis, liver spot)
ink-spot lentigo (reticular lentigo, reticulated black solar lentigo)
Becker’s nevus (pigmented hairy epidermal nevus)
Further reading
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Diagnostic atlas of melanocytic pathology
epheliDes
Ephelides or freckles are very common and develop as a con­
sequence of sun exposure. They present as small, uniformly
pigmented macules measuring 1 or 2 mm in diameter. The
face, upper chest, and the backs of the arms and hands are
particularly affected (Fig.
1.1).
Ephelides are often conspicu­
ous in people with fair skin, red hair and blue eyes. The pres­
ence of large numbers correlates with an increased risk of
developing melanoma.
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Increased pigmentation of epidermis (Figs
1.2 and 1.3)
Normal epidermal architecture
Melanocytes diminished or present in normal numbers
Lesions developing on a background of severe actinic
damage should not be confused with lentigo maligna
(Figs
1.4 and 1.5)
fig. .3 ephelis:
there is increased basal cell pigmentation, and melanin is also
evident in the overlying keratinocytes. Melanocytes are present in normal numbers.
fig. . ephelis:
multiple brown macules. (Courtesy of St John’s Institute of
Dermatology, London, UK.)
fig. .4 ephelis:
this example comes from the sun-damaged skin of an elderly
patient.
fig. . ephelis:
the epidermis appears normal. Note the hyperpigmentation.
fig. .5 ephelis:
basal cell hyperpigmentation is present. There is no evidence of
melanocyte atypia. Solar elastosis is evident.
epheliDes anD lentigo
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lentigo simplex
Simple lentigines are not related to sun exposure. They are
very common and develop in childhood and adolescence,
presenting as 1–5 mm diameter uniformly pigmented mac­
ules. There is no site predilection and the mucosae may be
affected (Fig.
1.6).
Large numbers of lentigines are a feature
of a variety of conditions, including Peutz–Jeghers, multi­
ple lentigines (LEOPARD), Laugier–Hunziker, LAMB and
Bannayan–Riley–Ruvalcaba syndromes, Addison’s disease,
Carney’s complex, familial generalized lentiginosis and cen­
trofacial lentiginosis.
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fig. .6 lentigo simplex:
dark brown, well-defined macule. (Courtesy of St. John’s
Institute of Dermatology, London, UK.)
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Elongation of rete ridges (Fig.
1.7)
Increased pigmentation of basal layer (Fig.
1.8)
Increased number of melanocytes
Macromelanosomes occasionally encountered
Absence of cytological atypia
Pigment incontinence
Superficial perivascular lymphohistiocytic infiltrate
Coexistence of junctional activity (lentiginous junctional
nevus)
fig. .7 lentigo simplex:
the epidermis is hyperpigmented and there is
characteristic elongation of the rete ridges.
fig. .8 lentigo simplex:
increased numbers of cytologically normal melanocytes
are present.
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Diagnostic atlas of melanocytic pathology
pUVa, sUnbeD anD raDiation
lentigines
Long-term treatment of a variety of disorders, including pso­
riasis and vitiligo with PUVA (psoralen plus ultraviolet A)
therapy, may be associated with the development of lentigi­
nes. Lesions are typically multiple and present as darkly pig­
mented, highly irregular macules with a predilection for the
shoulders, upper back and limbs (Fig.
1.9).
Sunbed lentigines
are related lesions which are encountered after exposure to
UVA for tanning purposes.
Radiation lentigines developing after accidental exposure
to ionizing radiation may be a related condition.
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Ephelide-like features
Lentigo-like features (Fig.
1.10)
Rarely melanocytic nuclear hyperchromatism,
pleomorphism and multinucleation
PUVA lentigines are not associated with malignant potential.
fig. .0 pUVa lentigo:
this example shows typical elongation of rete ridges and
hyperpigmentation.
genital melanosis anD lentigines
Genital hyperpigmentation may present as multiple, often
multifocal, irregular areas affecting both skin and mucous
membranes (melanosis) or as more discrete lesions (genital
melanotic macules) (Fig.
1.11).
Genital lentigines are a fea­
ture of Laugier–Hunziker disease, Carney’s complex and
Bannayan–Riley–Ruvalcaba syndrome.
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Increased pigmentation of basal layer of the epidermis
(Fig.
1.12)
Lentigo-like features
Absence of melanocyte cytological atypia
Absence of junctional activity
fig. .9 pUVa lentigo:
multiple dark brown macules after treatment for psoriasis.
(Courtesy of St John’s Institute of Dermatology, London, UK.)
fig. . Vulval melanosis:
there is irregular mucosal
hyperpigmentation.
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epheliDes anD lentigo
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acral lentigo
Acral lentigines are small, circumscribed, uniformly pig­
mented macules that present on the palms and soles and
beneath the nails. They may also be encountered on the dor­
sal surface (Fig.
1.13).
They are more commonly encountered
in dark-skinned races. They are not associated with develop­
ment of acral melanoma.
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Increased pigmentation of epidermis (Figs
1.14 and 1.15)
Normal epidermal architecture
Melanocytes diminished or present in normal numbers
fig. . Vulval melanosis:
note the basal cell hyperpigmentation and pigmentary
incontinence.
fig. .3 acral lentigo:
a small pigmented macule is present on the dorsal surface
of the fourth toe. (Courtesy of Dr Vincent Liu, University Iowa Hospital, Iowa, USA.)
fig. .4 acral lentigo:
increased basal pigmentation is evident.
fig. .5 acral lentigo:
high-power view.
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