Surgical Pathology Criteria–

Nephrogenic Adenoma

Differential Diagnosis

Nephrogenic Adenoma Urothelial Papilloma
Papillae lined by single layer of cells, frequently hobnailed Papillae lined by normal multilayered transitional epithelium
No umbrella cells Normal umbrella cells present
Usually associated with tubular submucosal component No associated tubular component

Nephrogenic Adenoma Papillary / Polypoid Cystitis
Papillae lined by single layer of cells, frequently hobnailed Papillae lined by normal multilayered transitional epithelium
No umbrella cells Normal umbrella cells present
Usually associated with tubular submucosal component No associated tubular component

Nephrogenic Adenoma Clear Cell Adenocarcinoma
Generally tightly packed uniform acini/tubules Tubules/acini generally more variable in size and distribution
Cytologically quite bland Cytologically atypical
Nucleoli inconspicuous if present Nucleoli may be prominent
No invasion of muscularis propria May invade muscularis propria

Nephrogenic Adenoma Prostatic Adenocarcinoma
Generally tightly packed uniform acini/tubules Tubules/acini generally more variable in size and distribution
Cytologically quite bland Cytologically atypical
Nucleoli inconspicuous if present Nucleoli may be prominent
PSA and PrAP negative Prostate markers positive in virtually all gland forming prostatic adenocarcinomas
Can be a problem especially in the prostatic urethra, or post surgery/TURP (papillae frequently lost) and because both are racemase/AMACR positive and p63 and HMWCK negative

Nephrogenic Adenoma Cystitis Cystica/Glandularis
Tubules lined by single layer of cuboidal cells, frequently hobnailed Cysts lined by normal multilayered transitional epithelium, with or without lumenal glandular differentiation
Usually associated with papillary component No associated papillary component
p63, HMW cytokeratin negative p63, HMWCK positive

Nephrogenic Adenoma Fibroepithelial Polyp
Lined by single layer of cells, frequently hobnailed Lined by normal multilayered transitional epithelium
No umbrella cells Normal umbrella cells present
Usually associated with tubular submucosal component Submucosal component if present is cystitis cystica/glandularis

Nephrogenic Adenoma with Fibromyxoid Stroma Urothelial Carcinoma with Chordoid Features
Areas of typical nephrogenic adenoma (papillae and tubules lined by single layer of cuboidal cells) Areas of usual transitional carcinoma
p63 negative p63 positive
In the fibromyxoid areas these may be identical

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