Renal Papillary Adenoma
Epidemiology and Etiology:
- 10% incidence in ages 21-40 and 40% incidence in
ages 70-90
- More common in kidneys bearing papillary RCC
than in normal kidneys
- Renal vascular disease more common to have
adenomas
- Chronic tobacco use correlation
- Long-term haemodialysis
- 33% of patients with acquired cystic disease
- 14% in patients undergoing transplant for
end-stage renal disease
- Hereditary papillary renal cancer – adenomas are
common
Common sites:
Gross features:
- < 15mm (by definition)
- pale yellow-gray
- discrete, well-circumscribed nodule
- unencapsulated
- numerous adenomas rarely (renal adenomatosis)
Histologic features:
- note that histologic appearance is identical to
low-grade papillary renal cell adenocarcinoma
- ISUP grade must be 1 or 2
- corresponding closely to types 1 and 2
papillary renal cell carcinoma
- size and encapsulation criteria are the only
distinction from low-grade papillary RCC (ISUP grade 1-2)
- complex, branching, papillomatous
structures with numerous complex fronds
- may also have tubules, glands, cords, sheets
- cuboidal to polygonal cells
- regular, small, central nuclei
- stippled to clumped chromatin
- inconspicuous nucleoli
- nuclear grooves maybe
- no atypia
- mitotic figures absent or rare
- scanty cytoplasm
- pale, amphophilic to
basophilic
- less frequently, voluminous eosinophilic
cytoplasm resembling type 2 papillary RCC
- psammoma
bodies common
- foamy macrophages common
Immunophenotype:
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Marker:
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Sensitivity:
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Specificity:
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EMA
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Most
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LMWK
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Most
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HMWK
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Most
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AMACR
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Usually
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Molecular features:
- cytogenetics similar to papillary renal
carcinoma
- trisomies
7 and 17 often
- loss of Y often
- presence of additional abnormalities is highly
suggestive of malignancy
Other features:
- Unencapsulated
WHO ISUP grade 1-2 tumours < 15 mm have
virtually no capacity to metastasize
- Not a contraindication for renal transplantation
(at least < 5 mm)
References:
- Eble
JN, Sauter G, Epstein JI, Sesterhenn
IA. (eds.) WHO Pathology &
Genetics: Tumours of the Urinary System and
Male Genital Organs (2004)
- Moch
et al. (eds.) WHO Classification
of Tumours of the Urinary System and Male
Genital Organs (2016)