Abstract
BACKGROUND: Composite tumors are neoplasms comprising two distinct, yet intermingling, cell populations. This paper reports a rare phenomenon where early gastric signet-ring cell carcinoma (SRCC) and gastric mucosa-associated lymphoid tissue (MALT) lymphoma coexist within the same lesion. CASE SUMMARY: A 40-year-old woman presented to the West China Hospital for examination, which revealed a whitish, shallow, and uneven mucosal lesion in the stomach. The lesion was diagnosed as a poorly differentiated adenocarcinoma, including SRCC with atypical lymphoid hyperplasia associated with Helicobacter pylori infection, based on histopathological examination of the biopsy specimen. The lesion was excised using segmental gastrectomy. However, histological examination of the surgical specimen confirmed that it was a poorly differentiated gastric adenocarcinoma with features of SRCC and MALT lymphoma. These two entities were stage I and coexisted in the same lesion. CONCLUSION: It is uncommon for gastric SRCC and MALT lymphoma to coexist without distinct borders. Surgical resection is effective for these lesions.