Urothelial carcinoma of the bladder in childhood is extremely rare. We report on a 12-year-old girl with urothelial carcinoma of the bladder who presented with gross hematuria. Immunohistochemical staining showed normal levels of cytokeratin 20 expression and decreased levels of Ki67 and p53 expression. Human papillomavirus, which can be a cause of urothelial carcinoma of the bladder, was not d...

AIM To investigate whether immunohistochemical staining for cytokeratin 20 (CK20) and thyroid transcription factor 1 (TTF-1) is useful in distinguishing Merkel cell carcinomas (MCCs) from metastatic small cell carcinomas (SCCs). METHODS Eleven cases of MCC and 10 of lung SCC were stained for CK20 and TTF-1. RESULTS Ten of 11 MCCs stained with the antibody to CK20. None was positive for TTF-...

An endoscopic examination revealed a mass in the distal esophagus of a 9-year-old intact male bulldog. Histopathologically, the mass was composed of cuboidal to columnar neoplastic epithelial cells and extended from the squamous epithelium of the esophageal mucosa, indicating that the tumor was derived from Barrett's esophagus. Moreover, highly atypical foci that exhibited a cribriform pattern ...