A 28-year-old woman consulted for this lesion on her right arm.

 Clinical picture

Dermoscopic picture

Dermoscopy revealed a targetoid lesion:

• a central globular pattern (black arrow) in favor of a melanocytic nevus
• a peripheral ecchymotic halo (red arrow)
• a central hemorrhagic crust (yellow arrow)

This lesion was a hemosiderotic targetoid nevus.

Asymmetric pigmented lesion on a leg

A 25-year-old woman consulted for this pigmented lesion on her right leg.

Dermoscopy revealed:

• asymmetry of color
• atypical reticular network

Pathology was in favor of a melanoma in situ developed on a melanocytic nevus.

Symmetric blotch

Fig 1 Blotch

A blotch (fig 1)  is a dark-brown or black structure-less area where other dermoscopic features cannot be seen. Symmetric blotches are in favour of benign lesions. Assymetrically distributed blotches are in favour of melanomas.

In our case, the blotch was symmetrically disposed and a peripheral reticular network was visible. This kind of blotch is also called black lamella.

This lesion was corresponding to a benign melanocytic nevus.

It has to be distinguished from the blue structure-less pattern or blue homogeneous pattern of a blue nevus (fig 2).

Fig 2 Blue homogeneous pattern

Plantar nevus

A 25-year-old woman consulted for a pigmented lesion on her right foot.

Dermoscopy revealed a parallel furrow pattern and a whitish structureless area.

On the middle of this structureless area a keratotic lesion was noticed in favor of a callus.

An excision was performed and pathology revealed a benign melanocytic nevus.

The structureless area was caused by the chronic friction of this nevus against shoes.

Whitish area

A 17-year-old girl presented a pigmented lesion with a lateral  depigmentation.

Dermoscopy  revealed a globular pattern associated with a whitish structureless area. On this whitish area some vessels were observed. There were no signs of peppering.

This lesion was excised and pathology revealed a benign dermal melanocytic nevus with a fibrous involution.

Whitish structureless area can be observed in:

• fibrous involution
• after traumatism
• in case of regression (with peppering)

Arborizing tree vessels

A 79-year-old woman consulted for this lesion near her right ear. This lesion was soft and non ulcerated. The patient did not remember how long it was evolving.

Dermoscopy revealed a homogeneous pattern with many arborizing vessels.

The lesion was excised and pathology was in favor of a benign melanocytic nevus


Arborizing vessels are mainly found in basal cell carcinomas and also rarely in the following lesions:

• melanocytic nevus
• melanoma
• seborrheic keratosis
  

Collision tumor

A patient presented a pigmented lesion on his back (lumbar area). He had no idea of change of colors or size and this lesion had not been traumatized.

Picture taken with a Fotofinder dermoscope

Dermoscopy revealed a peripheral reticular-globular pattern with a central hypopigmentation in favor of a benign melanocytic nevus.

Picture taken with a 3Gen Dermalite Foto System Pro

At the inferior pole of the lesion, a red structureless area was noticed in favor of a cherry angioma.

The association of these to lesions, namely melanocytic nevus and cherry angioma corresponded to a collision tumor.

Picture taken with a Fotofinder dermoscope

Picture taken with a 3Gen Dermalite Foto System Pro

A collision tumor is defined as a side-by-side occurence of two tumors (benign or malignant).

For example: confluence of a seborrheic keratosis and a basal cell carcinoma, confluence of a melanoma and a BCC, confluence of an angioma and a Clark nevus.

Hypopigmentation

Hypopigmented areas are frequently observed in melanocytic nevi.
In this case, hypopigmentation was associated with a typical reticular pattern.
In melanocytic nevi, hypopigmentation is often patchy, multifocal and perifollicular.

Globular pattern

Typical globular pattern with a rim of globules.
This benign melanocytic nevus does not need an excision.

Nevus spilus

A 25-year-old woman consulted for a pigmented lesion on her right arm.
The lesion was a lentiginous patch with darker brown pigmented macules in favor of a nevus spilus.
Dermoscopy revealed darker brown areas with a reticulo-globular pattern in favor of melanocytic nevi. The background was light brown and reticular.

Nevus spilus are present at birth or childhood. On histology they correspond to a lentigo with surimposed junctional or compound nevi.
Main differential diagnosis is agminated nevus which correspond to lentiginous compound melanocytic nevi without light background pigmentation.

Reference: Bragg et al. Agminated acquired melanocytic nevi of the common and dysplastic type. J Am Acad Dermatol 2005;52:67-73

Collision tumor

A 57-year-old man consulted for a bi-coloured lesion on his back.



Dermoscopy revealed a typical reticular pattern and some brown globules (red circle) in favor of a melanocytic nevus and a lighter brown pigmentation (green circle) without pigment network. Delicate fat fingers were present on this part in favor of a seborrheic keratosis.

The lesion was excised and pathology confirmed the diagnosis of collision tumor which associated a seborrheic keratosis and a melanocytic compound nevus.

A collision tumor is defined as a side-by-side occurence of two tumors (benign or malignant). For example: confluence of a seborrheic keratosis and a basal cell carcinoma, confluence of a melanoma and a BCC, confluence of an angioma and a Clark nevus.

Rim of globules

A 16-year-old boy consulted for his nevi after summer holidays. Dermoscopy revealed 3 nevi with rim of globules. This dermoscopic feature is often seen after sun exposition and in enlarging nevi.

Breast nevus

A 18-year-old woman consulted for this enlarging nevus on her left breast (the nipple is upper, not seen on the clinical picture).




Dermoscopy revealed an atypical reticular network with "funny lines" . A possible explanation of this aspect could be the enlargement of the breast during the pregnancy 3 months before. No dermoscopic sign in favor of a melanoma was detected.
After discussion with experts in dermoscopy a 3-month follow-up was scheduled.

Exophytic papillary structures

This 50-year-old patient has a soft polypoïd tumor on her left breast in favor of a Unna nevus
Dermoscopy revealed typical exophytic papillary structures,
comma-like vessels and a positive wobble sign.

Unna nevus

A 39-year-old woman consulted for an abdominal pigmented lesion.
Dermoscopy revealed exophytic papillary structures (*), clustered milia-like cysts (black circle), comedo-like openings (blue circle).
The wobble sign was present in favor of a Unna nevus.
The wobble sign is a useful sign when it is difficult to share between a Unna nevus and a seborrheic keratosis: the dermoscope put on the lesion is moved; if the lesion wobbles, it is a Unna nevus at the difference of a seborreic keratosis which does not wobble.

Blue nevus

A 32-year-old woman consulted for this blue lesion on her nose.
Dermoscopy revealed an homogeneous blue pattern in favor of a blue nevus.

Enlarging nevus

A 13-year-old girl consulted for a scapular enlarging nevus at the end of summer.


In dermoscopy (x20), the lesion was well defined, with a symetric globular pattern.

The main sign was a symetric peripheral rim of globules, suggestive of a benign enlarging nevus.

The management consisted in a yearly follow-up.


Dermoscopy (x50): brown globules at the periphery