Background: Basal cell carcinomas (BCC), being the most common diagnosed skin cancer in Australia, are frequently encountered in routine practice. Rarely, these tumours occur concurrently with melanomas, given the common risk factor of UV radiation.

Aims We aimed to perform a systematic review of the literature to elucidate clinicopathological features of lesions containing both a basal cell carcinoma and a malignant melanoma and to present a case report of a melanoma metastasizing into a basal cell carcinoma.

Methods: A comprehensive review was conducted using Pubmed, Embase and Cochrane databases, using the terms “basal carcinoma and melanoma,” “basal cell carcinoma invading melanoma,” “basal cell carcinoma collision with melanoma,” “melanoma invading basal cell carcinoma,” “melanoma colonizing basal cell carcinoma” Clinco-pathological data was extracted including patient demographic data (gender, age), size and location of BCC, Breslow depth and type of melanoma.

Results & Conclusions: 48 studies have been included in this article with a total of 55 cases of basal cell carcinoma occurring concurrently with melanoma. Most cases occurred in males (n = 42 compared to females n = 13), with a mean age of 71.3 ±15.1 years. The mean diameter of the BCC component was (25.8 ± 21.8 mm) and the mean Breslow depth of the melanocytic component was (3.1 ± 5 mm). Most lesions occurred on the face (n = 17). Understanding, clinicopathological features underpinning collision tumours allows us to stratify at risk sub-groups. This is particularly pertinent given the rarity of collision tumours.

We present these findings in the context of a case of an 85-year-old male with a lesion on his right temple, later found to be a metastatic melanoma from a scalp primary invading into a nodular basal cell carcinoma.