Dear readers of AJSP: Reviews and Reports,
We are delighted to present the current issue of the journal, which is a combination of our traditional, topic-centered approach—this and the following issues are dedicated to thyroid pathology—along with unsolicited case reports. These case reports are not organ or disease centered and will continue to be added to the thematic issues, as well as published online. As usual, all of these will have undergone a rigorous peer and editorial review and were selected to support the educational mission of our journal.
Thyroid pathology has been an area of active—and successful—basic and clinical research, and numerous breakthroughs have been achieved in the diagnosis, triage, and management of thyroid conditions. It is surprising, therefore, that despite these successes diagnostic thyroid pathology remains just about as challenging today as it was decades ago. This is why we have devoted two consecutive issues of AJSP: Reviews and Reports to recent developments and important lessons in thyroid pathology.
The first issue of our thyroid pathology series is dedicated to molecular diagnostic modalities in thyroid pathology and cytopathology. We start with two review articles devoted to new and fascinating additions to our diagnostic armamentarium in the area of thyroid cytopathology. Thyroid fine-needle aspiration biopsies have been steadily increasing in volume, and while benign and malignant ends of the diagnostic spectrum are relatively well defined, the indeterminate diagnostic categories still remain difficult in terms or their ability to predict behavior and triage patients to conservative versus operative management. Molecular diagnostic methods, such as mutational analysis of thyroid aspirates, have been marketed to provide additional information to help stratify risk in these circumstances; however, the sensitivity and specificity of these mutational profiles have left much to be desired. C. Narick et al address two important issues hindering the usefulness of thyroid cytopathology: interobserver/intraobserver and sample variability. The authors describe recent updates to National Comprehensive Cancer Network guidelines, specifically as they concern the triage and management of indeterminate thyroid cytology samples. Dr Narick and colleagues' review also addresses the use of direct smears as substrate for molecular testing. Finally, this review offers a comprehensive and detailed comparative summary of all commercial molecular assays currently on the market. The review by A. Banizs and colleagues takes this topic further and describes the underpinning of MiRNA profiling and practical issues in the use of miRNA-based classifiers in risk stratification of indeterminate thyroid nodules.
The complexity of thyroid pathology is further illustrated by the fascinating report provided by Al-Hashimi, and Diaz-Cano uses a rare case of Hashimoto thyroiditis, giving rise to both classic papillary thyroid carcinoma and hyalinizing trabecular adenoma. The authors use molecular and immunohistochemical techniques to illustrate the complex interplay of molecular events in the neoplastic initiation of thyroid tumors and show the molecular link between the nonneoplastic inflammatory processes and cancer. The next case report reminds the readers to always be on guard when examining neck lymph nodes: an incidental finding of metastasis of previously undiagnosed papillary thyroid carcinoma found in lymph node dissection performed for oral squamous cell carcinoma is that teachable moment that papillary thyroid carcinoma metastases can be subtle and unexpected.
The remaining case reports in this issue are not related to thyroid pathology. They represent a mix of interesting cases with lessons applicable to everyday practice of pathology. L. Harinath and coauthors present a case of a composite tumor of the rectum, consisting of a small cell carcinoma along with conventional adenocarcinoma. The authors present a very useful and practical summary of classification and diagnostic criteria of neuroendocrine carcinomas of the lower gastrointestinal tract. K. Stashek and colleagues describe a case of sarcomatoid hepatocellular carcinoma and provide a thorough, superbly organized and utterly practical review of malignant spindle cell tumors of the liver—a difficult topic made easier by these expert authors.
Dr Jenkins and colleagues describe a rare case of late metastases of endometrial stromal sarcoma with discordant high-grade morphology and molecular abnormalities typical of low-grade tumors. This case discusses the current classification of endometrial stromal sarcomas, including their underlying genetic translocations; however, the most important teachable moment in this report illustrates that endometrial stromal sarcoma needs to be considered in the differential diagnosis of metastatic tumors even in patients with no previous diagnosis of this malignancy and that careful gross examination of hysterectomies for leiomyomas is necessary to avoid a missed opportunity to treat these tumors. The last case report illustrates a rare condition—an ectopic thymoma within the right atrium; this well-documented report discusses the hypotheses of origin of ectopic thymomas in various locations, making it an interesting read.
We hope that the readers enjoy this first installment of the thyroid pathology updates, as well as the assorted case reports, and find them educational and useful in their practice.