Merkel cell carcinoma arising on a pre-existing Bowen's disease: is it just by chance?

Merkel cell carcinoma (MCC) is a cutaneous carcinoma with neuroendocrine differentiation. It arises typically on sun-exposed areas of elderly men as an asymptomatic, rapidly growing, red nodule. Although it is usually found as a solitary nodule, in almost one third of cases MCC may be associated with other malignancies such as basal cell or squamous cell carcinomas. Merkel cell carcinoma should be considered as differential diagnosis every time we have a rapidly growing, red nodule, arising in an elderly patient with signs of sun-damage. We report a case of MCC developing in association with a pre-existing Bowen's disease. The association between MCC and Bowen's disease is quite common and their area of occurrence is usually a sun-exposed area. Ultraviolet radiation contributes to the etiology of both the malignancies.