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.