Answer: All of the above

Histology: Throughout all layers of the bladder and extending out of the bladder is an infiltrate of single loosely cohesive cells. Most of the cells are round with bland nuclei and a rim of eosinophilic cytoplasm. Some cells have clear vacuoles. These vacuoles lacked mucin on special stains.

Discussion: For these cases we add the following note: There is a group of urothelial carcinomas with the unifying feature being infiltrating, loosely cohesive relatively bland cells. The cytoplasm variably has rhabdoid, plasmacytoid or signet-ring cell features. These tumors often resemble infiltrating lobular cancer of the breast.

Tumors with rhabdoid and plasmacytoid features are a recognized variant of UC. Signet-ring cell cancer is a variant of adenocarcinoma. However, in some cases one has a tumor composed of individual cells which don’t have these cytoplasmic features yet have the same loosely cohesive widely infiltrative growth pattern. They are probably all part of the same spectrum of tumor and have a very poor prognosis. In the current case, there were metastases to 5/10 lymph nodes in keeping with the typical behavior of these lesions.