Dermatofibroma

Typical assciation of a central white patch with a peripheral pigmentation (not reticulated ) in a dermatofibroma

Other cases of dermatofibromas
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Blue nevus

Typical blue homogeneous pattern* in favour of a blue nevus.

* synonym: blue structure less pattern

Atypical (dysplastic) nevi

A 19-year-old man consulted for multiple atypical (dysplastic nevi or Clark nevi) on her trunk. Three of them were clustered on her back. They featured three different dermoscopic patterns:

1-reticulo-globular pattern with eccentric hyperpigmentation

2 - multicomponent pattern (globular, reticular and homogeneous patterns)

3- reticular pattern with central hypopigmentation

Hairpin blood vessels

A 52-year-old man consulted for this inguinal exophytic pigmented tumour.


Dermoscopy revealed fissures and ridges (black rectangle) and a vascular pattern with many hairpin blood vessels (red rectangle).

Pictures taken with Fotofinder dermoscope

Hairpin blood vessels and fissures and ridges were in favor of a seborrheic keratosis.

Hairpin blood vessels are quite typical of seborrheic keratoses (particularly if there is a white halo surrounding them) but are non specific and can be found also in:

• melanocytic nevi
• keratoacanthomas
• basal cell carcinomas
• melanomas (often thick and irregular)
  

Arborizing vessels

A 65-year-old man consulted for a red tumor on his forehead.

Dermoscopy revealed arborizing vessels and an ulceration which confirmed easily the diagnosis of basal cell carcinoma.

Pictures taken with 3Gen Dermlite Foto System Pro

 On the 2nd picture above, the dermoscope caused a higher pressure on the tumor and vessels appeared less apparent than on the first one.

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

Hypopigmentation is a very common sign seen in atypical nevi (dysplastic nevi) .
Hypopigmented areas are devoid of structures, lightly pigmented, and comprise at least 10% of the surface area. Hypopigmented areas are sometimes observed around follicles in common nevi and congenital nevi.
In atypical nevi, these areas are located centrally whereas in melanomas they are most often seen at the periphery.

Case 1: central hypopigmentation and peripheral reticular pattern in an atypical nevus

Case 2: multiple areas of hypopigmentation and reticular pattern in an atypical nevus

Case 3: patchy multifocal hypopigmentation in an atypical nevus


Case 4: hypopigmented areas around follicles in a melanocytic nevus

Fibrillar pattern

A 48-year-old woman noticed a pigmented lesion on the right side of her right foot.
Dermoscopy revealed a fibrillar pattern in favor of a benign acral melanocytic nevus.

Fibrillar pattern is a variant of parallel furrow pattern.

Combined nevus

A 16-year-old girl consulted for a melanocytic nevus with 2 colors located on her back.
Dermoscopy revealed a globular pattern associated with a central homogenous pattern (darker area) in favor of a benign combined nevus.

A combined nevus is a nevus which contains two or more components, most often with 2 distinct colors.
In some cases combined nevus consists of a typical blue nevus associated with another kind of nevus.
A combined nevi can clinically mimick melanomas because of the markedly variegated coloration and asymmetry suggestive of a melanoma occuring on pre-existing nevus.
Dermoscopically , combined nevi present with a multicomponent pattern (homogenous, reticular and globular in combinations )
If a combined nevus is composed of a blue nevus and a common nevus, dermoscopy reveals the stereotypical findings of a blue nevus, namely ( homogenous blue-gray pigmentation without observable local features)

Seborrheic keratosis (keratotic subtype)

A 72-year-old man was referred for this scaly lesion on his scalp.

Clinical and dermoscopic evaluation were in favor of a keratotic type of seborrheic keratosis.


Dermoscopy revealed:

• an unspecific pattern (white to yellow horn masses over a background brown coloration)
  
• peripheral hairpin vessels
  

Seborrheic keratoses in most cases are clinically and dermoscopically diagnosed.

Main dermoscopic signs are:

• milia-like cysts
• comedo-like openings (crypts, pseudo follicular openings)
• fissures and ridges ("brain-like" or cerebration's appearance)
• fingerprint-like structures
• moth-eaten border
• hairpin blood vessels
• network-like structures
• sharp demarcation
• fat fingers
  

In the keratotic subtype of seborrheic keratosis an unspecific pattern is frequently observed and, because of the exaggerated ortho-hyperkeratosis, local features are not visible.
In our case, dermoscopic examination reveals hairpin blood vessels which is a typical local sign of seborrheic keratosis.

Keratoacanthoma

A 72-year-old man consulted for a rapidly enlarging tumor on his right forearm. The lesion appeared 3 to 4 months before.


The main clinical diagnosis was a keratoacanthoma.

Dermoscopy revealed:

• a central brownish structureless area corresponding to a central mass of keratin
• a whitish area with presence of elongated hairpin vessels
  

A central brownish structureless area (black circle) and hairpin vessels on a whitish background (white circle) are the two main dermoscopic signs in favor of a keratoacanthoma.

The diagnosis was confirmed by pathology after the complete excision of the tumor.