Surgical Pathology Criteria

Florid von Brunn Nests

Differential Diagnosis

Florid Cystitis Cystica and/or Glandularis NOS Florid von Brunn Nests
Nests are predominantly cystic Nests are predominantly solid
These form a spectrum and the distinction is not important

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)

Inverted Papilloma Florid von Brunn Nests, Cystitis Cystica/Glandularis
Regular pattern of anastomosing cords and trabeculae Round nests, may show fusion
Peripheral palisading and central streaming Lacks biphasic palisading/streaming pattern
Criteria above apply to both solid and cystic processes
An older description of inverted papilloma composed of cystic nests (Kunze) may not be separable from florid von Brunn nests

Urothelial Carcinoma with Inverted Growth Pattern Florid von Brunn Nests, Cystitis Cystica/Glandularis
Usually has a surface papillary component Surface normal
Cytologic features and disorder of carcinoma, appropriate to grade Bland, uniform, orderly cells
Mitotic figures present, appropriate to grade No mitotic figures

Invasive Urothelial Carcinoma Florid von Brunn Nests, Cystitis Cystica/Glandularis
Single cell invasion Intact nests only
Jagged, irregular nests Round regular nests
Mitotic figures and atypia present, appropriate to grade No mitotic figures or atypia
Stroma may be desmoplastic No stromal response

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