Recent advances in anatomic pathology either drive or concur with advances in medicine. One example of this is that the companion diagnostics of immunotherapy are required for selected immunotherapy medications, which are not approved for use without the test. Therefore, practicing pathologists should understand and apply advances in pathology, particularly the emerging topics in the field. Researchers interested in experimental and clinical pathology should also strive to make an impact on patient care via changes in diagnostic pathology. How to best understand and advance diagnostic pathology for patient care? I personally feel that one reasonable answer is to focus on new entities, new diagnostic criteria, and new (bio)markers. Fortunately, a group of excellent anatomic pathologists share this opinion and have joined the cause. In this inaugural annual special section on emerging topics in anatomic pathology (ETAP), they attempt to focus on these 3 aspects of ETAP.

LiVolsi and Baloch describe the noninvasive follicular thyroid neoplasm with papillary nuclear features (NIFTP) in depth. They succinctly review NIFTP's separation from follicular variant of papillary carcinoma of the thyroid, its evolution, and its current definition and pathologic characteristics. Importantly, several emerging, if not yet established, related entities are discussed, including multifocal NIFTP, microNIFTP (1 cm or less), and tumor features whose clinical significances remain largely unknown.

The World Health Organization (WHO) classification of tumors of the digestive system was updated recently, but its clinical significance and usefulness are unclear. Assarzadegan and Montgomery share selected updates on neuroendocrine neoplasms, appendiceal tumors, and molecular advances in tumors of the digestive system. Their work will surely answer many questions and clarify doubts on how to best interpret and use this new WHO classification of tumors of the digestive system.

Liquid biopsy is a new modality in pathology and is becoming increasingly important in cancer care. Tay and Tan provide us with a timely review on liquid biopsy in breast cancer, including the detection of circulating tumor DNA and tumor cells. Specifically, they summarize the uses of liquid biopsy for early diagnosis, prognostication, monitoring treatment response, detecting minimal residual disease, and stratification of progression risks. These insights may be applied to other tumors.

Recent studies show that patients with advanced-stage or recurrent human epidermal growth factor receptor 2 (HER2)–positive endometrial serous carcinoma may benefit from trastuzumab plus chemotherapy. Indeed, this combined therapy has been endorsed by national guidelines. However, the characteristics of HER2 protein expression and gene amplification in these tumors are poorly understood by pathologists. To address this knowledge gap, Buza compares and discusses the HER2 scoring criteria in breast, gastric, colorectal, and endometrial carcinomas. She also proposes an easy-to-use algorithm for scoring HER2 expression in these endometrial tumors.

Several pan-cancer biomarkers, such as microsatellite instability, neurotrophic receptor kinase (NTRK) fusion, and high tumor mutation burden, and their associated cancer drugs were recently approved in the United States. Additional pan-cancer markers and modalities are also emerging in the field. Given their increasing use in clinical practice, these markers may be important and interesting for practicing pathologists. Therefore, Yao et al introduce the recently approved and emerging pan-cancer biomarkers or multi-histology biomarkers, and discuss their testing methodologies, limitations, and treatment eligibilities. This review is aimed to increase the awareness of these pan-cancer biomarkers among general pathologists. Its easy-to-read tables hopefully may serve as a useful reference for readers.

Finally, Al-Obaidy and the late David Grignon provide an in-depth review on primary amyloidosis of the genitourinary tract. The statistics and patient characteristics are elegantly summarized. They also describe some unusual associations of primary amyloidosis with other genitourinary diseases based on literature review and their institutional experience. We are deeply saddened that David passed away right before the completion of this manuscript, which will likely be the concluding publication of his legacy.

I very much thank our immediate-past editor-in-chief, Philip T. Cagle, MD; the other advisory committee members of the ETAP; the authors; and the reviewers. I am also grateful to Patrick Kearns, Katie Giesen, and Hilary Price at the editorial office of the Archives of Pathology & Laboratory Medicine for their outstanding editorial skills and excellent editorial assistance. If you have any suggestions on future topics, please feel free to contact me via email. Your input on ETAP is much appreciated.

Author notes

The author has no relevant financial interests in the products or companies described in this article.