Clinical features of multiple myeloma patients with isolated extramedullary relapse.

This study sought to analyze the clinical features and prognosis of multiple myeloma with isolated extramedullary relapse and with the absence of systemic progression. The clinical features and outcome were retrospectively analyzed in six multiple myeloma patients. These patients had secretory multiple myeloma at diagnosis. When relapsed, the dissociation between medullary and extramedullary response was detected. The serum or urine monoclonal component was extremely low or absent. The plasma cells in bone marrow were <5%. All patients received new targeted therapies (thalidomide or bortezomib) before extramedullary relapse. It is difficult to achieve second remission for them. Even in those showing response, the duration of response was extremely short. The median of overall survival from diagnosis and from extramedullary relapse was 19 months and 6 months, respectively. The overall survival was significantly shorter compared to the patients without extramedullary involvement (84 months, P=0.001). These patients exhibited a special and rare relapse pattern. Patients with this relapse pattern were resistant to current therapies, including novel targeted agents and associated with poor prognosis.