Florid von Brunn Nests
Definition
- Benign urothelial process composed of markedly increased submucosal von Brunn nests
Diagnostic Criteria
- Strikingly increased numbers of round epithelial nests in the lamina propria
- Generally large nests
- Regular spacing of nests
- Lacks irregular infiltrative pattern
- May be lobular or linear
- Deep border of process shows generally uniform depth of nests
- May be hard to assess on biopsy specimens
- Lesions in ureter and pelvis may be composed of crowded smaller and more irregular nests
- Mild atypia at most
- May have occasional prominent nucleoli
- Cystic change may be prominent
- Cystitis cystica has spaces lined by transitional cells
- Cystitis glandularis has spaces lined by columnar cells with apical glandular differentiation but retention of urothelial base
- Frequent overlap and no significant clinical difference between the two and no significance to their presence
- A glandular variant of inverted papilloma has been described
(Kunze)
- Round urothelial nests with spaces with glandular differentiation
- This may not be separable from florid von Brunn nests / cystitis glandularis (Picozzi)
- Moderately atypical lesions may be seen following irradiation or chemotherapy or rarely in their absence (Lane)
- Features raise the possibility of nested carcinoma
- Smaller, more irregular nests
- Infiltrative pattern at base
- No invasion of muscularis propria
- Moderate nuclear pleomorphism
- Nucleoi may be prominent
- Mitotic figures infrequent
- Stromal changes indicate reactive nature
- Acute and chronic inflammation
- May have ulceration
- Hemorrhage with fibrin and hemosiderin
- Ectatic thin walled vessels intimately associated with epithelial nests
- Edema and fibrosis
- No desmoplastic response
- Acute and chronic inflammation
- Features raise the possibility of nested carcinoma
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates: 10/20/12, 2/5/13
