Leptomeningeal relapse in primary cutaneous DLBCL : Implications for a prophylactic CNS therapy

Background Isolated leptomeningeal relapse in a case of cutaneous lymphoma is an uncommon event more so in a case of primary cutaneous diffuse large B‐cell lymphoma (PCDLBCL). This phenomenon is of great significance as the subsequent prognosis becomes poor and the prophylactic central nervous system (CNS) therapy if administered, can reduce the chances of relapse, however, the survival benefit remains uncertain. The role of prophylactic CNS therapy is not well defined in the case of PCDLBCL. Case We report a case of PCDLBCL leg type with a low CNS International Prognostic Index (CNS‐IPI) risk, who developed isolated leptomeningeal relapse in the form of bilateral facial nerve palsy. He was managed by 2nd line chemotherapy and CNS directed therapy and achieved complete remission. Conclusion PCDLBCL leg type is an aggressive malignancy. Molecular/genomic mechanism likely responsible for CNS dissemination should be identified by prospective multi‐centric studies that can better define the subsets of patients eligible for prophylactic therapy in the absence of a high CNS‐IPI risk.