A multicenter study of interobserver variability in pathologic diagnosis of papillary breast lesions on core needle biopsy with WHO classification

Hye Ju Kang, Sun Young Kwon, Ahrong Kim, Woo Gyeong Kim, Eun Kyung Kim, Ae Ree Kim, Chungyeul Kim, Soo Kee Min, So Young Park, Sun Hee Sung, Hye Kyoung Yoon, Ahwon Lee, Ji Shin Lee, Hyang Im Lee, Ho Chang Lee, Sung Chul Lim, Sun Young Jun, Min Jung Jung, Chang Won Jung, Soo Youn ChoEun Yoon Cho, Hye Jeong Choi, So Yeon Park, Jee Yeon Kim, In Ae Park, Youngmee Kwon

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Background: Papillary breast lesions (PBLs) comprise diverse entities from benign and atypical lesions to malignant tumors. Although PBLs are characterized by a papillary growth pattern, it is challenging to achieve high diagnostic accuracy and reproducibility. Thus, we investigated the diagnostic reproducibility of PBLs in core needle biopsy (CNB) specimens with World Health Organization (WHO) classification. Methods: Diagnostic reproducibility was assessed using interobserver variability (kappa value, κ) and agreement rate in the pathologic diagnosis of 60 PBL cases on CNB among 20 breast pathologists affiliated with 20 medical institutions in Korea. This analysis was performed using hematoxylin and eosin (H&E) staining and immune ohistochemical (IHC) staining for cytokeratin 5 (CK5) and p63. The pathologic diagnosis of PBLs was based on WHO classification, which was used to establish simple classifications (4-tier, 3-tier, and 2-tier). Results: On WHO classification, H&E staining exhibited 'fair agreement' (κ = 0.21) with a 47.0% agreement rate. Simple classifications presented improvement in interobserver variability and agreement rate. IHC staining increased the kappa value and agreement rate in all the classifications. Despite IHC staining, the encapsulated/solid papillary carcinoma (EPC/SPC) subgroup (κ = 0.16) exhibited lower agreement compared to the non-EPC/SPC subgroup (κ = 0.35) with WHO classification, which was similar to the results of any other classification systems. Conclusions: Although the use of IHC staining for CK5 and p63 increased the diagnostic agreement of PBLs in CNB specimens, WHO classification exhibited a higher discordance rate compared to any other classifications. Therefore, this result warrants further intensive consensus studies to improve the diagnostic reproducibility of PBLs with WHO classification.

Original languageEnglish
Pages (from-to)380-387
Number of pages8
JournalJournal of Pathology and Translational Medicine
Issue number6
StatePublished - Nov 2021

Bibliographical note

Publisher Copyright:
© 2021 The Korean Society of Pathologists.


  • Agreement rate
  • Core needle biopsy
  • Interobserver variability
  • Papillary breast lesion


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