Merkel cell carcinoma arising in immunosuppressed patients treated with high-dose ultraviolet A1 (320–400 nm) phototherapy: a report of two cases.

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumour of the skin. Though immunodeficiency is the most relevant risk factor, ultraviolet (UV) radiation is also involved, but as of yet we do not know the action spectrum, pattern or dose which would produce a dangerous exposure. A retrospective study of two immunosuppressed patients who developed MCC during, or soon after a treatment cycle with high dose UVA1 exposures was conducted, in order to understand wether repeated exposures to suberythemogenic UVA1 radiation may have a cancerogenic activity provoking MCC in immunosuppressed patients. [ABSTRACT FROM AUTHOR]