Papillary adenoma is unencapsulated tumor composed of cells with low ISUP/WHO grade arranged in papillary or tubular architecture and 15 mm in diameter or smaller (Umbreit and Thompson 2011). A diagnosis of papillary adenoma on needle biopsy should be made with extreme caution.
In autopsy series, papillary adenomas have been reported in approximately 10% of individuals (Caliò et al. 2019).
The frequency of papillary adenomas increased throughout adulthood.
Papillary adenomas are roughly five times more frequent in men than in women.
There is no site predilection.
Papillary adenoma is a clinically silent and incidental finding; a therapeutic approach is not required.
Papillary adenoma is a benign tumor.
Papillary adenomas arise in the renal cortex and often are subcapsular.
Papillary adenoma expresses CK7 and racemase.
Papillary adenomas frequently show trisomy 7 and 17 and loss of the Y chromosome (Brunelli et al. 2003).
The most important differential diagnosis is papillary renal cell carcinoma based on dimension and presence/absence of capsule.