Journal of Pathology and Translational Medicine

Original Articles

Prevalence of HER2-ultralow breast cancer in South Korea: a multicenter study by reassessment of HER2-zero cases: Min Chong Kim, Eun Yoon Cho, Hee Jin Lee, Ji Shin Lee, Jee Yeon Kim, Wan Seop Kim, Chungyeul Kim, Sun-Young Jun, Hye Jeong Choi, So Mang Lee, Ahrong Kim, Ji-Young Kim, Jeong Yun Shim, Gyungyub Gong, Young Kyung Bae; J Pathol Transl Med. 2026;60(2):184-192. Published online February 23, 2026; DOI: https://doi.org/10.4132/jptm.2025.10.22

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Abstract PDF Supplementary Material: Background
This study aimed to determine the prevalence of human epidermal growth factor receptor 2 (HER2)–ultralow breast cancer among cases initially classified as HER2 immunohistochemistry (IHC) 0 and assess interobserver variability in interpreting low-level HER2 expression. Methods: In this multicenter retrospective study, all invasive breast cancer cases diagnosed between January and December 2022 across 10 Korean institutions were retrieved. Institutional pathologists reexamined HER2 IHC slides originally reported as IHC 0 according to the 2018 American Society of Clinical Oncology/College of American Pathologists guidelines and reclassified them as HER2-null (0), HER2-ultralow (0+), or HER2-low (1+). Slides from 10% of HER2-null and HER2-ultralow cases were digitized for central review and independently assessed by two pathologists, with discrepancies resolved by consensus. Results: Among 8,026 cases, 2,836 cases (35.5%) were initially reported as IHC 0. Upon re-review, 1,673 (59.0%), 1,139 (40.2%), and 24 (0.8%) cases were reclassified as HER2-null, HER2-ultralow, and HER2-low, respectively. The prevalence of HER2-ultralow breast cancer varied considerably across institutions (23.7%–78.1%). Central review of 268 digitized cases showed concordance in 193 cases (72.0%). Among the 75 discordant cases, 54 tumors (72.0%) were upgraded from HER2-null to HER2-ultralow, and 18 (24.0%) tumors were upgraded from HER2-ultralow to HER2-low. Furthermore, two tumors (2.7%) were downgraded from HER2-ultralow to HER2-null. Conclusions: Approximately 40% of cases initially categorized as IHC 0 were reclassified as HER2-ultralow. The substantial inter-institutional variability observed in interpreting low-level HER2 expression highlights the need for standardized training and quality assurance to ensure accurate identification of patients eligible for HER2-targeted antibody–drug conjugates.

Current state of cytopathology residency training: a Korean national survey of pathologists: Uiju Cho, Tae Jung Kim, Wan Seop Kim, Kyo Young Lee, Hye Kyoung Yoon, Hyun Joo Choi; J Pathol Transl Med. 2023;57(2):95-101. Published online March 14, 2023; DOI: https://doi.org/10.4132/jptm.2023.01.06

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Background
Although the Korean Society for Cytopathology has developed educational goals as guidelines for cytopathology education in Korea, there is still no systematic approach to cytopathology education status for pathology residents. Furthermore, satisfaction with cytopathology education and with the outcome of the current training/educational program has not been investigated in Korea. This study aimed to obtain comprehensive data on the current state of cytopathology education for residents and evaluate education outcomes.
Methods
An online survey was conducted in December 2020 for the board-certified pathologists and training residents registered as members of the Korean Society for Cytopathology. The questionnaire comprised questions that investigated the current status of cytopathology at each training institution, the degree of satisfaction with the work and education related to cytopathology, outcomes of cytopathology training, and educational accomplishments.
Results
Of the participants surveyed, 12.3% (132/1,075) completed the questionnaire, and 36.8% (32/87) of cytopathology residents participated. The mean overall satisfaction with cytopathology education was 3.1 points (on a 1- to 5-point scale, 5: very satisfied). The most frequent suggestion among the free description format responses was to expand educational opportunities, such as online education opportunities, outside of the individual institutions.
Conclusions
Our results showed that cytopathology training in Korea needs further improvement. We expect that this study will inform systematic training of competent medical personnel armed with broad cytopathology knowledge and strong problem-solving abilities.

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Seung-Yeon Yoo, Yuri Hwang, Seokju Yun, Ok Hee Lee, Jiwook Jang, Youngjin Park, Tae Young Cho, Young Sin Ko
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Reviews

Molecular biomarker testing for non–small cell lung cancer: consensus statement of the Korean Cardiopulmonary Pathology Study Group: Sunhee Chang, Hyo Sup Shim, Tae Jung Kim, Yoon-La Choi, Wan Seop Kim, Dong Hoon Shin, Lucia Kim, Heae Surng Park, Geon Kook Lee, Chang Hun Lee; J Pathol Transl Med. 2021;55(3):181-191. Published online May 11, 2021; DOI: https://doi.org/10.4132/jptm.2021.03.23

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