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.