Rare Case of Spontaneous Regression in Primary Gastric Diffuse Large B Cell Lymphoma.

The spontaneous regression (SR) of primary gastric diffuse large B-cell lymphoma (PG-DLBCL) is extremely rare. Although the mechanism of SR is unclear, the host immune response, ischemia, or changes in the tumor microenvironment may play a role. On the other hand, SR does not indicate a complete cure and residual lymphoma may remain dormant, leading to relapse. This paper presents a rare case of an 82-year-old woman with PG-DLBCL who experienced SR without treatment, followed by a short-term relapse. In the present case, the most likely mechanism was biopsy-induced ischemia and increased apoptosis. This case underscores that, in PG-DLBCL with SR, the initial endoscopic findings are the most critical reference for an accurate diagnosis and proper management, but careful long-term follow-up and monitoring are necessary, given the risk of relapse.