Surgical Pathology Criteria

Nested Variant Urothelial (Transitional Cell) Carcinoma

Differential Diagnosis

Nested Variant Urothelial Carcinoma Transitional/Urothelial Carcinoma with Inverted Pattern
Invasive carcinoma that looks deceptively non-invasive due to predominantly nested pattern Non-invasive inverted pattern of carcinoma that looks deceptively invasive
Overall invasive pattern, not circumscribed Lacks clearly invasive pattern
May involve muscularis propria Does not involve muscularis propria
Varying sizes and shapes of nests Frequently formed by fusion of trabeculae and cords (inverted papilloma like pattern)
Desmoplastic stroma may be present No desmoplasia

Nested Variant Urothelial Carcinoma Inverted Papilloma
Overall invasive pattern, not circumscribed Circumscribed (if sample permits assessment)
May involve muscularis propria Does not involve muscularis propria
Varying sizes and shapes of nests Uniform trabeculae and cords
Disorder of cells in nests Orderly peripheral palisading and central streaming

Nested Variant Urothelial Carcinoma Florid von Brunn Nests, Cystitis Cystica/Glandularis
Infiltrative pattern Tend to have uniform depth and/or lobular architecture
Frequently invades muscularis propria Usually confined to superficial submucosa, does not involve muscularis propria
Overall cytologically bland but usually at least focally atypical Cytologically bland
Criteria above apply to both solid and cystic processes
The distinction may be very difficult on superficial biopsies
IPOX for Ki67, p53, p27 and CK20 is not helpful (Volmar)

 

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