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high-grade papillary urothelial carcinoma

(WHO/ISUP Classification, 2004)

Wednesday 30 March 2016

PO Webpathology

Definition: High-grade papillary urothelial carcinoma is a neoplasm with urothelium lining papillary fronds, a predominant disorderly pattern and moderate to marked architectural and cytologic atypia.

High-grade papillary urothelial carcinomas display total architectural disorganization and significant cytologic atypia of urothelium that can be recognized even at low power.

Images

- cytology of high grade urothelial carcinoma

- High-grade Urothelial carcinoma in prostatic ducts.

There is loss of nuclear polarity; considerable variation in nuclear size, shape, and chromatin content; mitoses are frequent and may be abnormal. Umbrella cells are usually absent.

The nuclei in this high-grade tumor are significantly enlarged and show variably increased chromatin content.

This high-grade papillary urothelial carcinoma shows highly pleomorphic cells with voluminous cytoplasm.

Pleomorphic nuclei with prominent nucleoli, frequent abnormal mitoses, and loss of cellular polarity and organization can be seen.

High-grade papillary urothelial carcinoma frequently display abundant apoptotic cells.

High-grade tumor can show little or no resemblance to urothelial cells. The exact histogenesis of high-grade urothelial tumors may be difficult to ascertain in metastatic sites. Clinical information may be of tremendous value in such cases.

The base of the tumor shows small isolated tumor cell nests which are beginning to infiltrate into the lamina propria.

Urothelial tumors are graded according to the worst [highest] grade present.

Invasion

The base of the tumor can show finger-like extensions into the lamina propria. The tumor cells at the invading front can have more abundant eosinophilic cytoplasm and show greater pleomorphism than the tumor cells on the surface - a phenomenon called paradoxical differentiation.

One of the most challenging tasks faced by pathologist reading bladder biopsies/transurethral resections is the correct identification of muscularis propria invasion.

It is critical to not confuse thin, delicate, discontinuous fascicles of muscularis mucosae for muscularis propria since patient with muscularis propria invasion may be offered cystectomy. Muscularis propria has thick fascicles.

Vascular invasion

The tumor cell clusters conform to the shape of the vessel. Immunostain for CD31 can confirm the presence of an endothelial lining around the space.

Vascular invasion should be distinguished from shrinkage artifact which would have no endothelial lining, blood, or lymphocytes.

Differenciation

Presence of focal or even extensive malignant squamous and/or glandular epithelium is not uncommon in typical urothelial carcinoma.

See also

- urothelial carcinoma