Kidney tumor

Benign adult tumors

Papillary adenoma

Editor-in-Chief: Debra L. Zynger, M.D.
Rola Saleeb, M.D., Ph.D.

Last author update: 10 December 2019
Last staff update: 28 September 2022 (update in progress)

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PubMed Search: "Papillary adenoma" kidney

Rola Saleeb, M.D., Ph.D.
Page views in 2022: 11,349
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Cite this page: Saleeb R. Papillary adenoma. website. Accessed February 5th, 2023.
Definition / general
Essential features
  • Benign papillary and tubulopapillary, low nuclear grade lesions of the kidney similar in morphology to papillary renal cell carcinoma type 1, however, lack pseudocapsule and are ≤ 15 mm
  • Based on available data, these lesions do not have the capability to metastasize
  • Prevalent in damaged and injured kidneys and could be related to a progenitor / stem cell-like renal tubular cell population that is increased upon kidney damage
  • Papillary adenomas are postulated to be precursor lesions to papillary renal cell carcinoma (RCC), however, the adenomas prevalence is much higher than carcinomas, indicating that many of them do not progress
  • Prior synonym: renal cortical adenoma
  • Renal adenomatosis for bilateral and multifocal cases
  • Renal cortex
  • Unknown, possibly secondary to renal injury as chronic medical renal diseases, pyelonephritis or nearby mass tumor effect (Am J Pathol 2019;189:2046 )
Clinical features
  • Imaging: usually CT scan, ≤ 15 mm, often not seen
  • Diagnosis by biopsy or resection, however, diagnosis on needle biopsy should be made with caution as capsule and grade heterogeneity may not be visualized (Eur Urol 2016;70:93)
Radiology description
  • Difficult to differentiate from other lesions using imaging
Prognostic factors
  • Benign lesions, thought to be precursor lesions of papillary RCC, however, the incidence of papillary RCC is much lower than papillary adenoma, indicating that not all cases have the potential to progress (Am J Pathol 2019;189:2046)
  • Size criterion changed from 5 mm to 15 mm in the WHO 2016 classification based on data that these lesions have no capacity to metastasize
  • Change allows for increased acceptance of donor kidney for transplantation, in which kidneys with papillary lesions ≤ 15 mm would not be rejected (Eur Urol 2016;70:93)
Case reports
  • 41 year old man with autosomal dominant polycystic kidney disease and renal papillary adenomas presented with unusual clinical presentation (Iran J Kidney Dis 2013;7:439)
  • 57 year old man with unusual imaging presentation of a papillary adenoma (Hinyokika Kiyo 2001;47:865)
  • Treatment is based on the presenting tumor or condition
  • Considered benign; does not, on its own, require treatment
Gross description
  • Depending on lesion size, smaller lesions might not be visible, larger lesions appear as well circumscribed, usually subcapsular, grayish-white to yellow nodules
Gross images

AFIP images

1.5 cm subcapsular tumor

Microscopic (histologic) description
  • Papillary, tubular or tubulopapillary architecture (Semin Diagn Pathol 1998;15:41)
  • Usually low grade nuclei corresponding to WHO / ISUP grade 1 to 2
  • Some would not consider the diagnosis of papillary adenoma if grade 3 nuclei (prominent nucleoli)
  • Lesions do not show pseudocapsule and are in direct contact to renal parenchyma
  • Cytoplasm amphophilic / basophilic and scant (similar to RCC, papillary type 1) (Mod Pathol 1997;10:537)
  • Some lesions show cytoplasmic clearing with fine cytoplasmic granularity similar to what is seen occasionally in papillary RCC tumors
  • Foamy macrophages and calcifications may be present
  • Papillary adenomas are benign lesions and are not graded
  • Lesions with clear cell RCC features should not be considered papillary adenoma
Microscopic (histologic) images

Contributed by Rola Saleeb, M.D., Ph.D.
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Papillary adenoma

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Contributed by Hsin-Yi Chang, M.D. and Jen-Fan Hang, M.D.
Type D papillary adenoma

Type D papillary adenoma

Positive stains
Negative stains
  • CAIX (positive in clear cell RCC)
Molecular / cytogenetics description
Molecular / cytogenetics images

Images hosted on other servers:
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FISH with gain of chromosome 12

Sample pathology report
  • Kidney, left, partial nephrectomy:
    • Papillary adenoma, 1.2 cm
  • Kidney, right, needle core biopsy:
    • Low grade papillary renal lesion, 0.6 cm
    • Comment: The differential diagnosis includes papillary adenoma and renal cell carcinoma, papillary type 1. Clinical correlation is advised as to the size of the lesion by imaging. A lesion ≤ 1.5 cm would be consistent with a papillary adenoma, while a lesion > 1.5 cm would be classified as a renal cell carcinoma, papillary type 1.
Differential diagnosis
Board review style question #1

    A 38 year old woman with recurrent pyelonephritis was found to have a 1 cm left renal mass on imaging. A biopsy of the lesion was performed that showed this morphology. Which of the following is the correct diagnosis and WHO / ISUP grade?

  1. Papillary adenoma WHO / ISUP grade 2
  2. Papillary adenoma, not graded
  3. Papillary renal cell carcinoma WHO / ISUP grade 1
  4. Papillary renal cell carcinoma WHO / ISUP grade 2
Board review style answer #1
B. Papillary adenomas are low grade lesions by morphology, however they are considered benign and are not graded as per the current guidelines

Comment Here

Reference: Papillary adenoma
Board review style question #2
    What are the chromosomal aberrations reported in papillary adenoma lesions?

  1. Trisomies of 7 and 17 only
  2. Trisomies of 7, 17 and loss of Y and less frequently gains in chromosomes 12, 16 and 20
  3. Trisomies of 7, 17 and loss of Y as well as deletions of the short arm of chromosome 3
Board review style answer #2
B. Papillary adenomas show chromosomal aberrations similar to papillary renal cell carcinoma, which include trisomies of chromosomes 7, 17, loss of Y and occasional gains in 12, 16 and 20. Chromosome 3p deletions are common in clear cell renal cell carcinoma

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Reference: Papillary adenoma
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