“…Similar to other organs, undifferentiated bladder carcinoma shows three different morphological expressions: undifferentiated carcinomas of the bladder with rhabdoid features, undifferentiated carcinoma NOS and osteoclast-rich undifferentiated carcinoma (Figure 7). 92,93,104,105,106 A rare and aggressive disease, undifferentiated carcinoma NOS of the urinary bladder refers to carcinomas that are composed of sheets or isolated undifferentiated cells with no specific pattern of differentiation identifying it as urothelial, squamous, adenocarcinoma or any other recognised category of bladder carcinoma. 92 Immunohistochemical staining demonstrates positivity, at least focally, with cytokeratin.…”