Papillary Hyperplasia in Autosomal Dominant Polycystic Kidney Disease: A Multi-Institutional Study With Immunohistochemical and Molecular Characterization
- Journal
- The American journal of surgical pathology (Q1)
- Published
- 4 August 2026
- Study design
- Cohort / observational study
- Evidence level
- Level 3, Low (CEBM 3b)
- Authors
- Kara S Tanaka, Sean R Williamson, Nicole Zalles, Douglas J Wu, Mahmut Akgul, Khaleel Al-Obaidy, et al.
- PMID
- 42548188
- DOI
- 10.1097/PAS.0000000000002592
Why clinicians should know about it
- Picked for Genetics (clinical) (paper of the day, 5 August 2026).
Abstract
Renal cysts in autosomal dominant polycystic kidney disease (ADPKD) frequently harbor small intracystic epithelial proliferations that arise in continuity with the cyst lining and are distinct from other recognized proliferative lesions or well-defined renal tumors and lack a formal designation. We aim to provide the histomorphologic, immunohistochemical (IHC), and molecular characteristics of these lesions, determine their incidence, and employ the term papillary hyperplasia (PH), consistent with the recent International Society of Urological Pathology (ISUP) consensus meeting report on precursor lesions of the kidney. A multi-institutional retrospective study of nephrectomies affected by ADPKD was reviewed for PH, histomorphologic features, and clinicopathologic data. PH was defined by intracystic tufted or papillary epithelial proliferations composed of a single layer of bland cuboidal epithelial cells with minimal amphophilic to eosinophilic cytoplasm. IHC stains and molecular analysis using whole-genome sequencing were performed on a subset of cases. Eighty-five nephrectomies from 48 patients demonstrated PH in 88% (75/85) of kidneys. Predominant architectural patterns were tufting (97%), papillary (72%), hobnail (72%), and micropapillary (51%). All PH exhibited low-grade nuclei without atypia, with amphophilic (95%) and/or eosinophilic cytoplasm (63%). The most well-developed PH per case measured 0.3 by 3.1 mm (mean height by width) and occurred within small cysts with an average diameter of 3 mm. PH were positive for KRT7, GATA3, L1CAM, variably positive for AMACR, and negative for CA9 and showed no definitive molecular alterations. PH are common microscopic findings in kidneys affected by ADPKD. PH show a distinct combined histomorphologic, IHC, and molecular profile.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.