Urothelial (Transitional Cell) Carcinoma In Situ (including flat hyperplasia and dysplasia)
Differential Diagnosis
- Principal differential diagnosis is vs reactive atypia
| Urothelial Carcinoma In Situ |
Reactive Atypia |
| Cytologically malignant |
Generally more uniform atypia, not clearly malignant |
| ≥25% of nuclei ≥5x size of lymphocytes |
Nuclei only 2x size of lymphocytes |
| Nucleoli if present usually variable, excentric |
Nucleoli usually uniform and centrald |
| Inflammation variably present |
Inflammation always present, acute or chronic |
| Mitotic figures may be atypical |
Mitotic figures may be frequent but not atypical |
Both may be either hyperplastic or largely denuded due to
sloughing
- Other diagnoses are generally resolved with additional sections, obtaining history of treatment, or careful attention to detail
- Radiation may result in full thickness atypia
- Frequently results in bizarre multinucleated cells
- Cytoplasm frequently vacuolated
- Stroma radiation fibroblasts may be present
- Intravesicular chemotherapy may produce markedly atypical surface epithelium
- Deeper cells are not affected
- Treated papillary carcinoma may lose tops of papillae resulting in largely flat lesions
- Most often seen with Mitomycin C and Thiotepa
