Skin collision tumour and dermoscopic diagnosis of melanoma in situ and dilated pore of Winer.

Collision tumours are a random association of two or more neoplasms arising in the same anatomical site. Dilated pore of Winer (DPW) - an adnexal tumour of pilar origin - has been described in collisions with basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and trichoblastoma. We present a literature review of melanoma-associated skin lesions and describe the first collision of a DPW with a melanoma in situ (MIS) and the sequential dermoscopic examination for diagnosis.