Characterization of Primary and Secondary Cutaneous B-Cell Lymphomas: A Population-Based Study of 4758 Patients

Introduction/Background: Cutaneous B-cell lymphomas are a heterogeneous group of rare malignancies whose specific site tropisms and site-specific survival have not been well documented. In this study, we seek to investigate the frequency and survival for primary and secondary cutaneous MZL (pcMZL and scMZL), primary and secondary cutaneous FCL (pcFCL and scFCL), and primary and secondary cutaneous DLBCL (pcDLBCL and scDLBCL) to better understanding their prognosis and natural history. Materials and Methods: A total of 4758 cases of CBCL diagnosed between 1975 and 2016 were identified in the SEER-18 database. Statistical analysis was performed to identify the frequency of location and survival. Results: pcMZL was disproportionately likely to present on the face and upper limb while those of scMZL approximated the expected ratios based on body surface area. pcFCL and scFCL were more likely to present on the face and scalp/neck. pcDLBCL and scDLBCL were more likely to present on the face, scalp/neck, and lower limb. Patients with systemic MZL or FCL, but not DLBCL, had significantly better survival than those diagnosed in the skin than at other sites. Conclusions: All of these lymphomas demonstrate site-specific tropisms and survival. Molecular characterization of cutaneous lymphomas with analyses of tumor microenvironment are the next steps in understanding disease biology.