Solitary metastasis of a Merkel cell tumor to the urinary bladder

The primary Merkel cell carcinoma, a neuroendocrine tumor, mostly appears on skin areas exposed to light. Complete excision with a safety margin plus local lymphadenectomy is the basic therapy. In cases of relapse or metastasis, surgical treatment is also the first choice. Chemotherapy or radiotherapy are used only for a palliative purpose. To date, in no case of metastasis has healing occurred. Lymphogenic and hematogenic metastasizing to the urinary bladder is rare, however infiltrating tumor growth into the urinary bladder occurs more frequently. In urology, the Merkel cell tumor has been detected only sporadically, while infiltration of the bladder has been described in three cases worldwide. We report the case of a patient with a single metastasis of a Merkel cell tumor in the urinary bladder, after excision of the femoral primary cancer two years earlier.