医网情深：纽约病理实习胃肠病例笔记四篇——在美国行医之路系列 YMQ， MD， PhD 何老师，这是我的第2、3和4篇胃肠病理实习笔记。写Case report真是练习描述病变和学习逻辑思维的好方法！感谢您把自己最宝贵的学习经验毫无保留地传授给我们！跟您学习已经整十天，我觉得自己每天都在进步！您循循善诱、深入浅出的专业辅导，还有从医学临床及面试文化、为人处事、价值观等方方面面的言传身教，以及针对我的个人经历和特点的个性化辅导，让我在不到两周的时间里脱胎换骨，信心倍增！衷心地谢谢您！ Histological diagnosis and differential diagnosis of GERD and Barrett’s Esophagus:  note 3 of pathology externship following Dr. Gang He YMQ， MD，PhD Histologically, the esophagus is lined by stratified squamous epithelium. Normally the basal layer is around one to two cell layers thick and the vascular papillae are confined to the lower one-third of the epithelium. In mild GERD, simple hyperemia (redness) may be the only endoscopic finding and the mucosal histology is often unremarkable. With the increase in severity, eosinophils are recruited into the squamous mucosa followed by neutrophils, accompanied by more severe histological characteristics. The main histopathological features of GERD include: 1 basal cell hyperplasia (>15% or 5 to 6 layers; the upper limit of the basal layer is regarded as the level above which the nuclei are separated by a distance greater than the nuclear diameter); 2 intraepithelial eosinophils (>1 to 2 eosinophils per × 40 high-power field); 3 Spongiosis (Dilated intercellular spaces); 4 elongated vascular papillae (vascular papillae reach the upper one-third of the epithelium or more than 50% of the thickness). 5 Other histological findings: balloon cell change (extension of squamous cell cytoplasm as a result of accumulation of plasma cell proteins), elongation of lamina propria papillae (extending into the upper third of the epithelium), keratinocyte vacuolization, an increase in intraepithelial lymphocytes, vascular lakes, and parakeratosis. Differentiation: 1 Eosinophilic esophagitis: Increased numbers of intraepithelial eosinophils, the presence of eosinophilic microabscesses or eosinophil degranulation should raise suspicion for this disease. Their abundance can help to differentiate from GERD. Their clinical features, such as lack of prominent acid reflux, irresponsiveness to high doses of proton pump inhibitors, and common comorbidities, such as atopic dermatitis, allergic rhinitis, asthma, can also help to differentiate.

2 Candida esophagitis: Even though neutrophils and lymphocytes can also be present in GERD, and severe reflux-induced erosion and ulceration can be associated with prominent neutrophilic infiltration. The presence of a superficial band-like neutrophilic infiltrate and an increase in intraepithelial lymphocyte numbers should raise the suspicion for Candida esophagitis. The presence of focal parakeratosis also deserves a search for fungal organisms.

Normal esophagus is lined by the stratified squamous epithelium. The H&E staining of this esophagus biopsy shows metaplastic changes, i.e., lined by columnar epithelium containing goblet cells (evidenced by the blue mucin staining in the cytoplasm in AB-PAS staining). Diagnosis of Barrett’s Esophagus (BE) requires both endoscopic and histologic findings. At endoscopy, Barrett mucosa appears orange-pink (salmon colored) and velvety in contrast to pale pink glossy squamous mucosa. Biopsies should be taken from the tubular esophagus located more than 1 cm above the gastroesophageal junction. The American College of Gastroenterology guideline requires endoscopically abnormal areas to show unequivocal intestinal-type epithelium with goblet cells (intestinal metaplasia) for the diagnosis of BE. Presence or absence of dysplasia should also be recorded. For those with endoscopically abnormal esophagus mucosa and negative AB-PAS staining (no blue goblet cells), the diagnosis of glandular GERD should be made. *In some countries, such as the United Kingdom and Japan, the presence of gastric cardiac-type epithelium which consists solely of mucus-secreting cells (clear to pale pink cytoplasm in AB-PAS staining and arranged in linear clusters along the epithelium) is considered sufficient for the diagnosis of BE. Reference: 1. Robbins and Cotran Pathologic Basis of Disease 9th Edition 2. Webpathology. http://webpathology.com/image.asp?n=7&Case=185 3. Haggitt RC (1994) Barrett’s esophagus, dysplasia, and adenocarcinoma. Hum Pathol 25:982–993.

Histological diagnosis and differential diagnosis of colorectal adenoma:  note 2 of pathology externship following Dr. Gang He   Tubulovillous adenoma：  Adenomas are intraepithelial neoplasms that range from 0.3 to 10 cm in diameter and can be pedunculated or sessile, with the surface of both types having a texture resembling velvet or a raspberry. The word “adenoma” means neoplastic polyp. “Neoplastic” suggests its malignant potential. This is in contrast to non-neoplastic (e.g., hyperplastic and Juvenile) polyps, which have no malignant potential. Colorectal adenomas are characterized by the presence of epithelial dysplasia. Comparing with the relatively normal epithelial cells (with small, uniform, basally located nuclei and abundant, mucin-filled cytoplasm) in black circle, dysplastic epithelial cells (in red circle) exhibit an increased nuclear-to-cytoplasmic ratio, hyperchromatic and elongated nuclei, nuclear pseudostratification and mucin-depleted cytoplasm. These changes are most easily appreciated at the surface of the adenoma and are often accompanied by prominent nucleoli, eosinophilic cytoplasm, and a reduction in the number of goblet cells. Notably, epithelial cells fail to mature as they migrate from crypt to surface. Adenomas can be classified as tubular, tubulovillous, or villous based on their architecture. Differential diagnosis: Hyperplastic polyps are composed of mature goblet and absorptive cells with no malignant potential. They have normal nuclear morphology. The serrated surface is the morphologic hallmark of these lesions. Sessile serrated adenomas overlap histologically with hyperplastic polyps, but are more commonly found in the right colon. Despite their malignant potential, sessile serrated adenomas lack typical cytologic features of dysplasia that are present in other adenomas, prompting some to refer to these lesions as sessile serrated polyps. Histologic criteria for these lesions include serrated architecture throughout the full length of the glands, including the crypt base, crypt dilation, and lateral growth. Intramucosal carcinoma occurs when dysplastic epithelial cells breach the basement membrane to invade the lamina propria or muscularis mucosa. Because functional lymphatic channels are absent in the colonic mucosa, intramucosal carcinomas have little or no metastatic potential and complete polypectomy is generally curative. Malignant polyp (submucosally invasive lesion) refers to a colorectal polyp including flat lesions with neoplastic invasion of the submucosa without extension into the muscularis propria. These lesions carry a risk of metastasis, and are considered “invasive adenocarcinoma”. In such cases, several factors, including the histologic grade of the invasive component, the presence of vascular or lymphatic invasion, and the distance of the invasive component from the margin of resection, must be considered in planning further therapy. References: 1. Robbins and Cotran Pathologic Basis of Disease 9th Edition 2. Endoscopic Recognition and Management Strategies for Malignant Colorectal Polyps: Recommendations of the US Multi-Society Task Force on Colorectal Cancer. Gastroenterology 2020;159:1916

A small cell neuroendocrine carcinoma-adenocarcinoma presented as a gastric ulcer: a case report——note 4 of pathology externship following Dr. Gang He   Case presentation： The patient is a 50-year-old male with a history of abdominal pain. Endoscopy showed a 2x2 cm gastric ulcer at the lesser curvature (Fig.1). An H&E staining (Fig.2) of the biopsy at the edge of the ulcer demonstrates focal adenomatous-type gastric epithelial dysplasia (hyperchromatic, elongated and pseudostratified nuclei and blue/pink staining cytoplasm, arrow in Fig.2) and absence of normal oxyntic glands. Some of the adenomatous-type structures in the lamina propria are arranged back-to back or in cribriform pattern, with pleomorphic nuclei (double arrows in Fig.2). There are several enterochromaffin-like cell clusters with small, hyperchromatic nuclei and scant pink/pale cytoplasm (asterisks in Fig.2). These cell clusters are variable in size, shape, density, and nucleus/cytoplasm ratio, mainly involve the lamina propria and show invasion through the muscularis mucosa. Focal prominent lymphocyte infiltration is also present.           The neuroendocrine origin of the enterochromaffin-like cell clusters is confirmed by the strong positive staining of chromogranin A (CgA, Fig.3), synaptophysin (Fig.4) and CD56 (Fig.5) and negative CK19 (Fig.6, which is only positive in the adenomatous-type structures). The positive MSH2 (Fig.7) and MSH6 (Fig.8) staining in both the enterochromaffin-like cells and the glandular cells excludes the diagnosis of Lynch syndrome. CD45 (Fig.9) immunostaining only highlights the lymphocytes and is negative in the tumor cells. This helps to exclude lymphoma. Ki67 (Fig.10) labeling index (LI) is 10-75% in both the enterochromaffin-like cells and the adenomatous-type cells, suggesting the highly proliferative property of this tumor.         Discussion： Neuroendocrine neoplasms (NENs) is a fast growing area of interest. To reduce the confusion caused by the differences in the classification of NENs among various organ systems, in the 2019 (the 5th edition) World Health Organization classification of tumors series, several changes were made in the classification of NENs. In the new classification for the NENs of the GI tract and hepatopancreatobiliary organs (table1), NENs are divided into well-differentiated neuroendocrine tumors (NETs) and poorly-differentiated neuroendocrine carcinomas (NECs), based on their molecular differences. The well-differentiated NETs are highly associated with MEN1, DAXX or ATRX mutations, whereas NECs usually have TP53 or RB1 mutations. NETs are graded into G1, G2 and G3 based on their mitotic rate and Ki67 index, while NECs are not formally graded, since they are considered high-grade by definition. NECs are continued to be separated into small-cell type (SCNEC) and large-cell type (LCNEC). When there is non-neuroendocrine component, the tumor is classified as Mixed Neuroendocrine-non-neuroendocrine Neoplasm (MiNEN). Even though the MiNEN are mostly high-grade, this conceptual category allows for the inclusion of low-grade tumors, and separate grading of the neuroendocrine and non-neuroendocrine component is recommended when feasible. When adenocarcinoma and neuroendocrine components both exist in a tumor and both account for at least 30% of the lesion, it can be named Mixed Adenoneuroendocrine Carcinoma (MANEC). MANECs are usually high-grade. NETs are also traditionally divided into 3 types based on both the clinical features (including the presence or absence of hypergastrinemia, atrophic gastritis, MEN1, Zollinger-Ellison syndrome, etc.) and the differentiation status of the cells.     The tumor in this case report has both NEC and adenocarcinoma component. Both components have high Ki67 index (> 20%). The adenocarcinoma component comprises less than 30% of the lesion and doesn’t match the MANEC criteria. So the diagnosis is MiNEN, specifically, mixed SCNEC-adenocarcinoma. Table1 Classification and grading criteria for neuroendocrine neoplasms (NENs) of the GI tract and hepatopancreatobiliary organs References: The 2019 WHO classification of tumors of the digestive system. Histopathology 2020, 76, 182–188. A case of mixed adenoneuroendocrine carcinoma (MANEC) arising in Barrett’s esophagus: literature and review. Surg Case Rep. 2018 Dec; 4: 45.