Chronic inflammation and immunosuppression lead to aging and tumorigenesis. T-helper 22 (Th22) cells, interleukin 22 (IL-22) and myeloid-derived suppressor cells (MDSCs) serve an important role in inflammatory-immune diseases and cancer. However, the status of Th22 cells, IL-22 and MDSCs in aging and elderly gastric cancer progression is unknown. In the present study, 39 elderly patients with gastric cancer (EGC), 32 elderly healthy controls (HE) and 31 young healthy controls (HY) were enrolled, and the peripheral Th22, Th17 and Th1 cells, and MDSCs, were examined using flow cytometry. Plasma levels of IL-22, IL-6 and tumor necrosis factor-α (TNF-α) were examined using ELISA. IL-22 protein levels in tumor tissues were examined using immunohistochemistry. There were increased numbers of peripheral Th22 and Th17 cells, and MDSCs, as well as increased plasma levels of IL-22, IL-6 and TNF-α in EGC compared with HE and HY. However, HE exhibited significantly increased levels of peripheral Th22 and Th17 cells as well as IL-6 and TNF-α compared with HY. Immunohistochemical analysis demonstrated that IL-22 protein accumulated in tumor cells and lymphocytes in the tumor microenvironment. The results obtained demonstrated that peripheral Th22 and Th17 cells as well as IL-6 and TNF-α plasma levels increased with aging. Furthermore, Th22 and Th17 cells, MDSCs, and IL-22 may be used as prognostic markers for identifying gastric cancer in elderly patients.

The majority of natural killer (NK)/T-cell lymphomas occur in the nasal cavity and rarely involve the stomach. They possess a specific immunophenotype, with the expression of cluster of differentiation (CD)56, CD2 and CD3ε, but without CD3 expression. Few cases of NK/T-cell lymphoma have partial CD30 expression. The present study reveals a unique case of a 41-year-old female patient with gastric NK/T-cell lymphoma that did not express CD56 and diffusely expressed CD30. Immunohistochemical staining demonstrated that the tumor cells expressed CD3ε, CD43, CD30 and granzyme B and did not express CD2, CD4, CD5, CD7, CD8, CD56, anaplastic lymphoma kinase, CD20, paired box-5 or pan cytokeratin. Based on the immunostaining profile and morphological features, the initial diagnosis considered was gastric anaplastic large cell lymphoma. However, following a consultation with other pathologists, the Epstein-Barr virus (EBV) status of the patient was investigated to exclude a diagnosis of NK/T-cell lymphoma. Notably, the signal for EBV RNA was diffuse positive. Therefore, the final diagnosis was corrected to NK/T-cell lymphoma. To the best of our knowledge, the present study is the first to report NK/T-cell lymphoma in the stomach with a diffuse CD30-positive and CD56-negative phenotype.