2020 Volume 19 Issue 3 Pages 180-184
An 85-year-old Japanese man presented with a growing nodule for four months. A clinical investigation revealed a 3 cm-sized, bloody, dark-red, dome-shaped nodule on the root of the nose. Dermoscopy detected milky red areas, crust, and linear irregular vessels. The remaining tumor was totally excised inorder to stop bleeding 2 days after the biopsy. Histologically, the tumor was domeshaped, and was composed of sheet-like basophilic nodule in the dermis. The tumor cells had small round nuclei with fine granular chromatin with ample cytoplasm. N/C ratio was high, and atypical mitoses could be detected. Immunohistochemically, tumor cells were positive for synaptophysin,chromograninA, CD56, CK20, and Merkel cell polyomavirus large T-antigen (clone : CM2B4). They were negative for CK7, CD31, D2-40 and TTF-1. The present case was diagnosed as Merkel cell polyomavirus-positive Merkel cell carcinoma. A postoperative radiotherapy was performed. Since the identification of Merkel cell polyomavirus inMerkel cell carcinoma in2008, its positive rates have beenreported to vary greatly betweencountries. Based onthe approval of anti-PD-L1 antibody avelumab for unresectable Merkel cell carcinomas, an accumulation of further cases and analyses are necessary in Japan. Skin Research, 19 : 180-184, 2020
