2019 Volume 34 Issue 1 Pages 50-56
A 63－year－old woman presented with a red nodule measuring 11 mm on her left lower leg. The nodule had gradually enlarged over the course of 1 year. A skin biopsy revealed Merkel cell carcinoma ; subsequently, the tumor was resected. During tumor resection, another red nodule measuring 5 mm appeared on the right cheek of the patient. This new lesion was also diagnosed as Merkel cell carcinoma on biopsy. This tumor was also resected and postoperative radiotherapy was performed. In this case, lesions appeared at anatomically distant sites on contralateral sides of the body in a short period of time. At a follow－up conducted 4 years later, there was no sign of distant metastasis to other organs. The prognosis of cancer depends on the tumor stage, which differs according to the relationship between the lesions. In this case, we evaluated the two lesions histopathologically and immunohistochemically, and found no difference between them. There was no difference in the expression of Merkel cell polyomavirus between the lesions, making it difficult to classify them as double primary or skin metastasis. [Skin Cancer (Japan) 2019 ; 34 : 50－56]
