Signet Ring Cell Carcinoma Mimicking Gastric Gastrointestinal Stromal Tumor: A Case Report

Epithelioid Subtype Gastrointestinal Stromal Tumors of Stomach in an Endoscopic Biopsy: A Potential Diagnostic Pitfall

Background

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract with a broad morphological spectrum. Although epithelioid GISTs account for 20% of GISTs, their morphological features may pose a diagnostic pitfall for pathologists due to their morphological similarities to poorly differentiated adenocarcinoma and lymphoma.

Case Presentation

Herein, we report a 65-year-old male patient with gastric epithelioid GIST misdiagnosed as adenocarcinoma for four years. During this period, he was treated with chemotherapy combined with PD-L1 immunotherapy. The clinicians thought the treatments were effective. However, there was no significant change in tumor size. The patient's clinical symptoms did not improve significantly as well. Finally, an endoscopic biopsy was performed again and gastric epithelioid GIST was confirmed in our hospital through morphology, immunohistochemistry, and whole-genome sequencing.

Conclusion

A broad morphological spectrum and diverse immunophenotypic changes of GISTs could represent a pitfall for pathologists. However, predisposed anatomical sites, morphology, and corresponding immunohistochemical markers are of great significance for the diagnosis of GISTs and the differential diagnosis from other diseases. On the other hand, clinicians should diagnose and comprehensively evaluate treatment effects based on the patient's clinical symptoms and relevant laboratory examinations, instead of over-reliance on pathological diagnosis.

Case Report: Clinicopathological characteristics of patients with gastric cancer with features of a submucosal tumour

Purpose

To investigate the clinicopathological characteristics, diagnosis and key points in the differential diagnosis of patients with gastric cancer (GC) with features of a submucosal tumour (GCSMT).

Methods

The clinical presentation and imaging findings of four GCSMT cases diagnosed at our centre from 2016 to 2021 were observed and their clinicopathological outcomes were analysed. The related literature was reviewed. Based on our collected data and the related literature, a total of 31 cases of GCSMT can be summarized.

Results

22 out of 31 cases did not present obvious symptoms and were accidentally discovered during gastroscopic examination. Only 10 patients experienced symptoms such as gastric discomfort, upper abdominal swelling and pain, haematemesis, or haematochezia. The male to female ratio was 22:9 and the age of onset ranged from 40 to 81 years (median age: 63 years). Tumours were located in the upper and middle third of the stomach (24/31), and in the lower third(7/31). The tumour diameter ranged from 0.6 to 7.3 cm, with an average value of 2.5 cm. Endoscopically, the disease manifested as SMTs, with the gastric mucosal surface appearing normal. Most patients underwent radical gastrectomy for GC (80.6%, 25/31). The pathological diagnoses of the 31 cases of GCSMT included well- and moderately-differentiated adenocarcinoma (6/31), poorly differentiated adenocarcinoma or signet ring cell carcinoma 6/31), mucinous adenocarcinoma (9/31), lymphoepithelioma-like carcinoma (7/31), gastric adenocarcinoma of the fundic gland type (3/31). Stage T1b and T2 tumours accounted for 56.7% (17/30) and 26.7% (8/30) of all cases. Lymph node metastases were found in six cases (20.0%, 6/30), whereas distant metastasis was not observed in any of the cases. For the 16 patients whose follow-up data were available, the follow-up time was 5-66 months, during which recurrence or metastasis was not observed.

Conclusion

GCSMT is a rare disease that is often difficult to accurately diagnose through endoscopic biopsy. The importance of gaining an understanding of this disease lies in differentiating it from other SMTs (mostly mesenchymal tumours) to avoid misdiagnosis and missed diagnosis and enable the early diagnosis and treatment of patients.

Canine Gastric Carcinomas: A Histopathological and Immunohistochemical Study and Similarities with the Human Counterpart

Simple Summary

Gastric carcinoma (GC) continues to be one of the leading causes of death in humans and is the most common neoplasm in the stomachs of dogs. In both species, previous studies have demonstrated that the disease is heterogeneous, with genetic and environmental factors playing a quintessential role in disease pathogenesis. Compared to humans, the incidence of gastric carcinoma in dogs is low although, in a small number of breeds, a higher incidence has been reported. In dogs, the etiology and molecular pathways involved remain largely unknown. This retrospective study reviews current signalment data, evaluates the inflammatory component and association with Helicobacter spp. presence in various canine gastric carcinoma histological subtypes, and investigates potential molecular pathways involved in one of the largest study cohorts to date. The benefit of such a comparative study is to highlight the parallel histological features and molecular pathways between dogs and humans.

Abstract

Canine gastric carcinoma (CGC) affects both sexes in relatively equal proportions, with a mean age of nine years, and the highest frequency in Staffordshire bull terriers. The most common histological subtype in 149 CGC cases was the undifferentiated carcinoma. CGCs were associated with increased chronic inflammation parameters and a greater chronic inflammatory score when Helicobacter spp. were present. Understanding the molecular pathways of gastric carcinoma is challenging. All markers showed variable expression for each subtype. Expression of the cell cycle regulator 14-3-3σ was positive in undifferentiated, tubular and papillary carcinomas. This demonstrates that 14-3-3σ could serve as an immunohistochemical marker in routine diagnosis and that mucinous, papillary and signet-ring cell (SRC) carcinomas follow a 14-3-3σ independent pathway. p16, another cell cycle regulator, showed increased expression in mucinous and SRC carcinomas. Expression of the adhesion molecules E-cadherin and CD44 appear context-dependent, with switching within tumor emboli potentially playing an important role in tumor cell survival, during invasion and metastasis. Within neoplastic emboli, acinar structures lacked expression of all markers, suggesting an independent molecular pathway that requires further investigation. These findings demonstrate similarities and differences between dogs and humans, albeit further clinicopathological data and molecular analysis are required.