Characteristics of 6 Cases of Overlapping Plasma Cell Disorders

BACKGROUND: Plasma cell disorders (PCD) are a group of diseases in which monoclonal plasma cells overproliferate and produce monoclonal immunoglobulins, including monoclonal gammopathy of undetermined significance, multiple myeloma, primary systemic light chain amyloidosis, extramedullary plasmacytoma, POEMS syndrome and so on. These groups of diseases are diagnosed according to signs, symptoms, laboratory examination and pathological manifestations, based on corresponding diagnostic criteria. It is generally believed that all kinds of plasma cell disorders exist independently and will not occur together. However, in clinic, we found that few patients can meet the diagnostic criteria of more than one kind of plasma cell diseases at the same time, and we named the diagnosis of such patients overlapping plasma cell disease.

Methods: This study retrospectively analyzed the characteristics of 6 cases of overlapping plasma cell disorders which were diagnosed in First Affiliated Hospital, Sun Yat-sen University.

Results: All 6 cases of overlapping plasma cell disorders were diagnosed with two plasma cell disorders at the same time at the onset. Among them, 5 cases were POEMS syndrome overlapping other plasma cell diseases, including 4 cases of POEMS syndrome overlapping solitary plasmacytoma and 1 case of POEMS syndrome overlapping active multiple myeloma (AMM). Another case was smoldering multiple myeloma (SMM) overlapping primary systemic light chain amyloidosis (pAL). All 6 patients were diagnosed strictly according to the diagnostic criteria, and they all met the diagnostic criteria of two plasma cell diseases. There are 3 males and 3 females, and the median age is 57 years old. Among them, the median plasma cells in bone marrow of 4 cases of POEMS syndrome overlapping solitary plasmacytoma were 2%, and no clonal plasma cells were found by flow cytometry. Plasma cells in bone marrow of patients with POEMS syndrome overlapping AMM and SMM overlapping pAL were 22% and 12%. The median level of VEGF of 5 cases of POEMS overlapping other plasma cell diseases was 441.38pg/ml. Of the 5 patients with POMES overlapping other PCDs, 3 received lenalidomide-based treatment, 2 received bortezomib-based treatment, and the patient with SMM overlapping pAL received Dara+Rd. The median follow-up time of these patients was 24 months. The median progression-free survival and median overall survival were not achieved.

Conclusion: Overlapping plasma cell disorders are a group of rare plasma cell diseases, which requires careful screening of various clinical manifestations, laboratory tests and pathological features for diagnosis. At present, it is difficult to diagnose this kind of disease, and we need to accumulate cases and experience.

No relevant conflicts of interest to declare.