The 16th Spring Seminar of the Korean Pathologists Association of North America

The Korean Pathologists Association of North America (KOPANA) was founded in 1992 for networking among pathologists of Korean heritage through professional interactions and also for fostering excellence and collaboration in education, research, and clinical practice of pathology by its members. KOPANA has also been recognized as a branch of the Korean Society of Pathologists (KSP), which was founded in 1946 and currently has about 1100 members in South Korea. Since 2001, KOPANA has held its spring seminar in conjunction with the annual meeting of the United States and Canadian Academy of Pathology. Speakers for KOPANA seminars encompass KSP members as well as KOPANA members to tap into the expertise on specific topics in 2 geographic areas. Our spring seminar has always been an excellent educational event for both KOPANA and KSP members.The 16th annual spring seminar of KOPANA was held in conjunction with the 106th annual meeting of the United States and Canadian Academy of Pathology, March 4–10, 2017, in San Antonio, Texas. In the past, our seminars have usually been focused on one organ system, such as gastrointestinal or gynecologic pathology. However, we took a different approach this time, covering recently described, clinically relevant entities in multiple organ systems. The lectures were to provide not only a high-level practical review but also a critical appraisal of important new entities or classification or paradigm shifts that have flooded the literature and overwhelmed practicing general surgical pathologists. This special section is the compilation of the lectures in this theme of our 16th KOPANA seminar, which should be very useful for day-to-day practice to meet clinical needs as well as to inspire novel ideas for further investigations. The 7 articles making up this special section will appear in 2 issues.Part I begins with an article by Lee. Lee provided a state-of-the art review on diffuse gliomas for nonneuropathologists. Specifically, the 2016 World Health Organization (WHO) update was summarized with great depth and clarity, which should help practicing pathologists and clinicians to understand the paradigm shift that is happening with the classification of gliomas. Currently the WHO system requires testing and listing key genetic alterations in diffuse gliomas as an integrated report in routine practice. Tables and figures in the review that are taken from the seminal papers are very effective in helping readers to comprehend the complicated concept, even for those who are not well versed in molecular pathology. In addition, the underlying biology and clinical significance of the IDH mutations are very well covered. More recently discovered mutations prevalent in diffuse midline gliomas of children and young adults are introduced as well. This review also provides readers with a glimpse of the inevitable future brought by the targeted next-generation sequencing approach.Koh and Cassarino updated us on p16 immunohistochemistry (IHC) in melanocytic lesions, including the useful data via meta-analysis. There is an unmistakable difficulty in distinguishing between benign and malignant melanocytic lesions for general surgical pathologists and dermatopathologists alike. Given the prevalent malpractice litigation in the United States associated with misdiagnosis of melanoma, mainly underdiagnosis, pathologists often resort to IHC. However, there is no magic marker to differentiate the 2 conditions. Among HMB45, Ki-67, and p16, which have been often used as a panel to differentiate benign from malignant melanocytic lesions, the role of p16 has been least known. Thus, the authors' update on p16 IHC via comprehensive literature review and meta-analysis is a great contribution to practicing pathologists. The tables to summarize the literature review with many representative illustrations were certainly very effective to introduce the finding in this less-known topic of p16 IHC in melanocytic lesions. Although the loss of p16 protein expression by gene mutation, deletion, or silencing may be a contributing factor in tumorigenesis akin to tumor suppressor genes/products, the use of p16 IHC for diagnostic purposes in melanocytic lesions appears to be limited as a single marker. When it is used in a panel of other melanocytic markers, however, the diagnostic utility of p16 IHC may increase.Cho and Song introduced to us a great insight via their critical assessment of the 2-tier grading system for laryngeal or oral squamous precursor lesions by WHO 2017 classification along with a review of reported clinical data. Interpretation of atypical squamous lesions of any head and neck mucosa poses a great challenge and often lacks a reasonable diagnostic reproducibility, especially in many grading systems for squamous intraepithelial lesions proposed in the past decades. The 2-tier grading system for laryngeal dysplasia by WHO 2017 will probably improve diagnostic reproducibility and clinical implication, though with the caveat that there is still a significant issue: the criteria for low-grade dysplasia do not allow a clear distinction from basal hyperplasia. Diagnostic utility of the WHO 2017 classification for oral epithelial dysplasia, on the other hand, remains unclear.Beginning part II is an article by Lee and Ro in which they provide a very comprehensive and clinically useful review on cribriform glands/ducts in the prostate for practicing surgical pathologists. The importance of recognizing such lesions becomes more critical given the fact that the spectrum of cribriform lesions encompasses benign, premalignant, and malignant conditions. Differentiation of these settings may be very difficult because their differences may be subtle and not so well known to practicing general surgical pathologists. Intraductal carcinoma of the prostate is a very important malignant condition with cribriform pattern, given its association with worse prognosis requiring prompt definitive treatment. This review gives great guidance to handle this spectrum of cribriform proliferation of the prostate by providing very relevant information on its clinical, prognostic, and treatment implications as well as practically useful tips for histopathologic differential diagnosis of these lesions for pathologists.Yi and Lee reviewed 2 highly contentious areas in lung cancer pathology: air space invasion (most widely known as spread through air spaces [STAS]) and Ki-67 IHC in lung carcinoid tumors. Although many studies have shown the clinical significance of STAS (primarily in lung adenocarcinomas), there are a few other studies raising serious doubt on its true nature and purporting STAS to be an artifact or mere epiphenomenon. Nonetheless, it would still be prudent for pathologists to be able to recognize STAS and differentiate from clear-cut artifacts given its current incorporation as an exclusion criterion in the diagnosis of minimally invasive adenocarcinoma by the WHO classification of tumors of the lung. Although Ki-67 is routinely recommended for use in nonpulmonary neuroendocrine tumors, current evidence does not warrant routine use of Ki-67 IHC in the differential diagnosis between typical and atypical carcinoid tumors of the lung. However, Ki-67 IHC may be a very useful adjunct in dealing with the differential diagnosis between lung carcinoid tumors and high-grade neuroendocrine carcinomas (small cell carcinoma and large cell neuroendocrine carcinoma) encountered in small biopsy specimens with crush artifacts.Cho and Kakar provided a complete overview of tumor budding in colorectal carcinoma (CRC). The concept of tumor budding in CRC is relatively new, but it has gathered extensive interest as an independent prognostic factor and has now been included as a reporting parameter in the College of American Pathologists Cancer Protocol implemented since January 2018. All important aspects that are extremely useful for pathologists are included in this review: early-stage tumor found as “malignant polyps” from preoperative biopsies, tumor budding in resection specimens, metastatic CRC, and methods of assessing tumor budding. Also, this review introduced the work of the International Tumor Budding Consensus Conference, which should be on our radar given its potential future influence on the American Joint Committee on Cancer system. Other practical issues are also covered, such as interobserver variability, peritumoral versus intratumoral budding, optimal stain, quantitation methods, and tumor budding in special tumor types (eg, signet-ring cell carcinoma, micropapillary carcinoma). This review should be a great handy resource for practicing pathologists whenever they have any question on tumor budding in CRC.Choi and Ro reviewed the histologic features and differential diagnosis of relatively common cutaneous spindle cell neoplasms based on their architectural (growth) patterns. The pattern-based diagnostic approach helps pathologists to arrive at a specific diagnosis or differential diagnoses of tumors and tumorlike lesions. This review provides a useful guide for practicing pathologists to diagnose cutaneous spindle cell neoplasms.On behalf of KOPANA and KSP, we would like to express our appreciation to the editorial board of Archives of Pathology & Laboratory Medicine for its invitation to publish the content of the lectures from our meeting in this forum. We hope this special section will be of great benefit to readers of the Archives of Pathology & Laboratory Medicine and practicing pathologists everywhere.

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