| One will occasionally find a tumor invading through the
bladder wall which lacks the distinctive features of differentiation which
will permit a specific diagnosis. "Undifferentiated malignant neoplasm"
may be the only diagnosis that is possible. Nowadays, particularly with
the use of immunohistochemistry, it is possible to specify that it is or
is not a carcinoma. If the H&E sections show an organoid growth
pattern and epithelial markers are positive (cytokeratin or epithelial
membrane antigen) then a diagnosis of carcinoma - as opposed to sarcoma,
melanoma, lymphoma - is possible. The diagnosis of undifferentiated
carcinoma will invariably imply a need for further studies to rule out
metastatic carcinoma. |
