10020-ML-1 SENTINEL LESION PRECEDING PRIMARY CENTRAL NERVOUS SYSTEM LYMPHOMA

Abstract

It has been reported that there are rare cases of spontaneous resolution, which are referred to as sentinel lesions in the early stages of primary malignant lymphoma of the central nervous system (PCNSL). In this study, we examined cases of PCNSL that presented with a sentinel lesion. Of the 43 PCNSL cases biopsied at our institution between 2011 and 2022, three cases were difficult to diagnose on initial biopsy. No preoperative steroids were used in all patients, and postoperative CT or MRI confirmed that the lesions were appropriately sampled from the targeted lesions. Since the diagnosis was not confirmed by the initial biopsy and symptoms were stable, the patients were followed up without chemotherapy, but symptoms worsened around 6 months later, and MRI showed recurrent large lesions. Another biopsy was performed in all patients, and a definitive diagnosis of diffuse large B-cell lymphoma (DLBCL) was finally obtained. It has been reported that sentinel lesions in PCNSL are characterized by demyelination or nonspecific inflammation on initial pathology and spontaneous resolution of lesions, which are estimated to be changes mediated by immunological mechanisms. In the present study, the course of symptoms was characterized by a relatively slow progression, and diffusion-weighted images at the initial onset did not show as high a signal as in usual PCNSL. Multiple biopsies are required to make a definitive diagnosis, and careful follow-up of symptoms and images and determination of the appropriate timing of biopsy are important.