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

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

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.

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.

Traumatized nevus

A 52-year-old woman used to be heavily sun-exposed during her holidays. Her husband noticed that a mole on her back was changing. Dermoscopically the lesion shows asymmetric colors and structures, a reticular and homogenous pattern and central area of hypopigmentation. Main hypotheses were an atypical (dysplastic) nevus with central hypopigmentation or a superficial spreading melanoma. The lesion was excised. Pathology revealed a traumatized benign junctionnal naevus. The patient did not remind any traumatism on this lesion. Melanocytic nevi can have atypical clinical and dermoscopic presentations in case of traumatism. This traumatism is sometimes not mentionned when taking the history

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)