Inverted Urothelial (Transitional Cell) Carcinoma
Definition
- Urothelial carcinoma that looks invasive but is not
Note
- Usual papillary urothelial carcinoma is covered separately
Diagnostic Criteria
- Features diagnostic of carcinoma must be present
- Disorderly maturation and loss of polarity
- Nuclear atypia/pleomorphism and mitotic activity
- At least 25% of tumor is composed of inverted growth patterns extending into submucosa
- Two main patterns, may be mixed
- Anastomosing cords and trabeculae
- Bulbous invaginations
- Nodules of carcinoma are smoothly circumscribed
- Basement membrane may be identifiable
- Peripheral cells may palisade
- Two main patterns, may be mixed
- Any of the following are evidence of invasion and exclude the diagnosis of inverted pattern
- Irregular, jagged nest shapes
- Single cell infiltration
- Disruption of basement membrane
- Desmoplastic stromal response
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 10/20/12
