Extraskeletal Ewing Sarcoma of the Gastrointestinal and Hepatobiliary Tract: Deceptive Immunophenotype Commonly Leads to Misdiagnosis.

Ewing sarcoma (ES) is an uncommon mesenchymal neoplasm that typically develops as a bone mass, although up to 30% arise in extraskeletal sites. ES of the gastrointestinal (GI) and hepatobiliary tract is rare and may be misdiagnosed as other, more common neoplasms that occur in these sites. However, the correct classification of extraskeletal ES is important for timely clinical management and prognostication. We reviewed our experience of ES in the GI and hepatobiliary tract in order to further highlight the clinicopathologic features of these neoplasms and document the potential for misdiagnosis in this setting. The archives and consultation files of 6 academic institutions were retrospectively queried for cases of ES occurring in the GI and hepatobiliary tract. The histologic slides and ancillary studies were reviewed and clinical data were retrieved for each case through the electronic medical records, when available. Twenty-three patients with ES in the GI and/or hepatobiliary tract were identified from 2000 to 2022. Of these, 11 were women and 12 were men with a median age of 38 years (range, 2 to 64). Tumor locations included the pancreas (n=5), liver (n=2), stomach (n=3), colorectum (n=3), and small intestine (n=5), as well as tumors involving multiple organs, pelvis and retroperitoneum (n=5). Tumor size varied between 2 cm and 18 cm. Twenty were primary and 3 were metastases. Of the 23 cases, only 17% were initially diagnosed as ES. The most common misdiagnoses involved various forms of neuroendocrine neoplasia due to expression of synaptophysin and other neuroendocrine markers (22%). A wide variety of diagnoses including GI stromal tumor was considered due to aberrant CD117 expression (4%). The diagnosis of ES was ultimately confirmed by detection of the EWSR1 rearrangement in 22 cases. The remaining case was diagnosed using traditional immunohistochemistry. Follow-up information was available in 20 cases, with follow-up time varying between 2 and 256 months. Six patients with follow-up died of disease between 6 and 60 months following initial presentation. Our data indicate ES in the GI and hepatobiliary tract is commonly misdiagnosed leading to a delay in therapy. In light of the attendant therapeutic and prognostic implications, ES should be considered in the differential diagnosis of any GI or hepatobiliary tumor with epithelioid and/or small round cell morphology

Gastric mesenchymal lesions other than gastrointestinal stromal tumor

Interpretation of gastrointestinal mesenchymal lesions involving the stomach and the remainder of the gastrointestinal tract is daunting but can be simplified somewhat merely by knowing in which layer they are usually found. For example, gastric Kaposi sarcoma is detected in mucosal biopsies whereas inflammatory fibroid polyp is nearly always in the submucosa. Gastrointestinal stromal tumors (discussed elsewhere in this issue) are generally centered in the muscularis propria. Gastric schwannomas are essentially always in the muscularis propria. Mesenteric lesions are usually found in the small bowel mesentery but the gastric mesentery is not immune. Knowledge of the favored layer is even more important in interpreting colon biopsies, since many mesenschymal polyps are encountered in the colon, but the same principle applies in the stomach. Herein we discuss several gastric mesenchymal lesions

Mesenchymal polyps

Most mesenchymal polyps are encountered in the colorectum but some characteristically arise in the oesophagus and stomach. Small bowel polyps are not often sampled but many of the types found in the other locations can be found in the small intestine and are covered elsewhere in this volume. Generally mesenchymal lesions of the tubular gastrointestinal tract that present as polyps are centred in the mucosa or submucosa. However, some lesions that are typically centreed in the muscularis propria are included since they are often confused with superficial lesions. Often the issues in interpreting such lesions revolve around whether the tumour is a gastrointestinal stromal tumour and whether it is a syndromic or sporadic, which has been addressed particularly for neural lesions

Diagnosis and Management of Barrett-Related Neoplasia in the Modern Era

Whereas in the past, pathologists were hesitant to diagnose high-grade dysplasia in patients with Barrett esophagus, because this diagnosis prompted esophagectomy, current international consensus is that endoscopic treatment is the management for high-grade dysplasia and intramucosal carcinoma. Furthermore, many centers advocate endoscopic ablation for low-grade dysplasia. As such, establishing a diagnosis of dysplasia has become the key step; separation between the grades of dysplasia is less critical. This article offers some criteria for separating dysplasia from reactive changes, discusses pitfalls in interpreting endoscopic mucosal resection specimens, and outlines management strategies

Histopathology of Barrett esophagus

Barrett esophagus (BE) is a metaplastic, premalignant lesion of the tubular esophagus that carries significant implications and is associated with approximately 0.5% annual cancer incidence. Although gastroesophageal reflux disease is a recognized risk factor, no clear guidelines exist as to who should undergo endoscopic screening for the condition. Histologic requirements for the diagnosis vary by geographic region with some but not all countries requiring the presence of goblet cells. In spite of interobserver variability, histologic assessment of dysplasia is currently the accepted method of surveillance and subsequent patient management is dictated by this evaluation. Though not universal, endoscopic therapy is rapidly replacing esophagectomy in patients with high-grade dysplasia/early carcinoma. This review aims to provide the reader with an overview on this subject with special emphases on the histopathologic features of BE and BE-associated dysplasia as well as evolution and new developments related to therapeutic modalities in patients diagnosed with dysplasia

Biopsy interpretation of the gastrointestinal tract mucosa

"One of the best-selling titles in the highly regarded Biopsy Interpretation Series, Biopsy Interpretation of the Gastrointestinal Tract Mucosa Volume 1: Non-Neoplastic, Fourth Edition, by Drs. Lysandra Voltaggio and Elizabeth A. Montgomery, provides practical, highly illustrated information on mucosal biopsies from the esophagus, stomach, small intestine, large intestine, and anus. Well-organized and highly readable, this fully revised volume offers the information you need to successfully navigate both common and unusual issues that arise in the day-to-day interpretation of gastrointestinal biopsies. Volume One focuses on non-neoplastic entities; also available is Volume Two, your complete guide to neoplastic gastrointestinal lesions"-- Includes bibliographical references and inde