A carcinoma in situ lesion of the usual type is seen in the bottom of the image. The stroma is involved by loosely cohesive neoplastic cells.
Areas of this tumor demonstrated glandular areas with abundant mucin.
At higher power, cytologic atypia of these loose glandular structures can be appreciated. Extracellular mucin is apparent
These mucinous, glandular areas blend into more conventional areas of transitional cell carcinoma.
Glandular or squamous differentiation generally occurs in about 10% of moderately or poorly differentiated invasive transitional cell carcinoma -- it is uncommon in well-differentiated non-invasive or only superfically invasive carcinomas. In glandular differentiation, the glands may appear small and tubular or irregularly shaped with mucin production.1
It is important to mention glandular differentiation in an otherwise usual-type transitional cell carcinoma for two reasons: (1) distinction from primary adenocarcionma of the bladder, which carries a poorer prognosis as they present at a later stage; (2) mention of a glandular component may be helpful if metastatic sites exhibit a glandular morphology.
1 Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 553.
2 Zhou M, Magi-Galluzzi, C. Genitourinary Pathology: Foundations in Diagnostic Pathology. Philadelphia, PA: Elvesier; 2006: 178.