Recurrence of Non-Hodgkin Lymphoma at the Insulin Injection Site: Case Report

This study sheds light on the effect of insulin, insulin-like growth factors (IGF), and their signalling receptors (IR and IGF-1R) on the progression of lymphoma. We report a case of a 64-year-old male with type 2 diabetes mellitus and a prior diagnosis of diffuse large B-cell non-Hodgkin lymphoma (DLBCL) treated with chemotherapy and local radiotherapy. Incredibly, four years post-treatment, the patient's DLBCL relapsed in the subcutaneous fatty tissue adjacent to the deltoid muscle of both the proximal left and right upper extremities, which were the sites he used to inject insulin. Insulin/IGF dysregulation can lead to tumour growth via angiogenesis. This mechanism is not limited to lymphoma and may contribute to the development of various types of cancer. While it is possible that DLBCL may have developed at the injection site either coincidentally, as a result of chronic inflammation, or potentially due to other factors that promote tumour growth, as we suggest in our case presentation, it is beneficial to emphasise the importance of tumour screening in diabetic patients, especially those receiving insulin injections. We therefore believe that regular screening of the insulin injection site should be included in routine consultations for these patients.