Nephrogenic Adenoma
Definition
- Benign tubular and papillary lesion of the urinary tract
Alternate Name
- Nephrogenic metaplasia
Diagnostic Criteria
- Most lesions have both a surface papillary and a submucosal tubular component
- Papillae are simple, with edematous core
- Tubules may be dilated or tightly packed and compressed
- May be surrounded by visible basement membrane
- Cystically dilated tubules may contain eosinophilic colloid like secretion
- May involve muscularis mucosae
- Rare description of muscularis propria involvement (Hansel)
- Papillae and tubules are both lined by a single layer of bland cells with pale to clear cytoplasm
- Papillary lining may be low columnar, cuboidal or hobnail cells
- Tubules typically cuboidal
- Tubule lining may flatten, giving microcystic, pseudovascular and/or signet ring like appearance
- Mucin stains negative in cells but secretions may stain
- Lining cells are typically bland, mitotically inactive
- Rare cases described with focal cytologic atypia
(Cheng 1999)
- Nuclei enlarged, hyperchromatic, may be multinucleate
- Nucleoli prominent
- Mitotic figures rare
- Rare cases described with focal cytologic atypia
(Cheng 1999)
- Frequently associated with inflammation clinically and histopathologically
- Some consider this to be a metaplastic lesion but it appears to represent implantation of urine borne kidney derived cells
- Variant with fibromyxoid stroma can simulate infiltrating adenocarcinoma
(Hansel)
- Epithelial cells compressed with spindle cell appearance
- Keratin positive
- Prominent mucin positive fibromyxoid stroma
- Typical nephrogenic adenoma present at least focally
- Cells are cytologically bland
- May be associated with prior treatment for carcinoma
- Epithelial cells compressed with spindle cell appearance
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting / last update: 11/23/14
