Vol 10, No 1 (2024)
Case report
Published online: 2024-01-21

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A collision tumour of basal cell carcinoma and melanocytic nevus mimicking a melanoma — a case report and review of the literature

Magdalena Żychowska1, Kinga Kołcz12, Ewa Kaznowska3
Forum Dermatologicum 2024;10(1):29-31.


A collision tumour is characterized by the presence of at least two different skin neoplasms in the same lesion. Collision skin tumours develop quite rarely. The case presents a 58-year-old woman in whom an asymmetric skin lesion of undetermined duration was noted during routine dermoscopy. The skin lesion consisted of two clinically distinct components. The patient remained under a 4-month follow-up. At the next visit, a change in the appearance of the previously present lesion was observed. The lesion was excised and submitted for histopathological examination, which was consistent with the diagnosis of a collision tumour composed of dysplastic nevus and basal cell carcinoma. This article discusses the characteristics and diagnostic difficulties in the diagnosis of collision tumours based on the available English literature. Furthermore, highlighted is the value of a non-invasive imaging modality which is dermoscopy in diagnosing not only melanoma and non-melanoma skin cancer but also complex lesions such as collision tumours.

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