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

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

Dysplastic nevus

A 34-year-old woman presented a Clark nevus (synonyms: atypical nevus or dysplastic nevus) on her back.


Dermoscopy revealed an asymmetric reticular-globular pattern.


Central globular pattern (circle) and reticular pattern (rectangle) are well seen on this picture.
The reticular-globular pattern is the most frequent of the different patterns observed in Clark Nevi.

Atypical nevus

This patient presented an atypical nevus with a reticular pattern and a central hypopigmentation.

Definition of atypical (dysplastic) nevus: nevus characterized by a diameter > 6mm, color variegations, and irregularity of the border. They have 3 global dermoscopic patterns, namely reticular, globular and homogeneous. Different combinations are possible, the reticular-globular one is the most frequent.

Atypical (dysplastic) nevus

A 68-year-old woman consulted for this pigmented lesion on her back.
Dermoscopy revealed an asymmetric lesion with an atypical reticular and homogenous pattern , a few subtle blue-white structures (circle) and brown dots (arrow)
The lesion was excised and pathology revealed an atypical (dysplastic) compound type.

Atypical (dysplastic) nevus with eccentric hyperpigmentation

Atypical nevus with eccentric hyperpigmentation is an atypical nevus of the utmost importance because its differential diagnoses are melanoma in situ and early invasive melanoma. In our case, the hyperpigmentation corresponded to a darker reticular network. In certain cases, the eccentric hyperpigmentation is a blotch.
This lesion was removed and the diagnosis of benign atypical nevus confirmed by the pathologist.

Atypical (dysplastic) nevus with multifocal hyperpigmentation

This is a case of atypical (dysplastic) nevus with multifocal hyperpigmentation giving a patchy appearance.
No melanoma-specific criteria were distinguishable.
A follow-up in 6 months was recommended.

Atypical (dysplastic) nevus with central hypopigmentation

This atypical (dysplastic) nevus was localized on the back of a 37-year-old man.
Dermoscopy revealed a reticular pattern with central hypopigmentation. Frequently the less pigmented centre corresponds to clinical papule (fried-egg type atypical nevus)

Atypical nevus

A 40-year-old man consulted for this atypical mole of the intermammary region, without recent changing.
Dermoscopy (x20) showed a combination of two patterns:

1-on the left: an homogenous pattern with comma vessels

2- on the right: a reticular pattern with blue white veil




The lesion was removed and pathology revealed a benign irritated compound nevus with lateral junctionnal extension