[Clinical characteristics analysis of patients with IgD type systemic light chain amyloidosis]

Objective: To analyze the clinical characteristics of patients with IgD type systemic light chain (AL) amyloidosis. Methods: The patients diagnosed with IgD-type AL amyloidosis at Peking University People's Hospital and the First Affiliated Hospital of Dalian Medical University from June 2013 to April 2023 (IgD group) were retrospectively included. These patients were matched with non-IgD type AL amyloidosis patients using a 1∶4 propensity score (non-IgD group). The general clinical data of the patients (age, gender, the type of light chain, results of relevant examinations and so on), treatment planss, and efficacy were collected (the corresponding sample size was reduced due to the fact that some patients did not undergo relevant examinations or lost testing data). Follow-up was conducted until August 2024 to compare the clinical characteristics of the both groups of patients. Results: A total of 45 patients were included in the study. The IgD group was comprised of 9 patients, with 6 males and 3 females, and an average age of (58±12) years. The non-IgD group consisted of 36 patients, including 24 males and 12 females, with an average age of (58±10) years. The overall median follow-up time [M (Q₁, Q₃)]was 58 (31, 84) months. In the IgD group, one patient had Kappa type while the remaining were Lambda type; seven cases involved kidney, and 6 cases involved heart. Two patients in IgD group had p53 deletion, but there was no p53 deletion in non-IgD group. The rate of soft tissue involvement [55.6% (5/9) vs 13.9% (5/36), P=0.025] and the level of free light chain difference (dFLC) (2 424 vs 140 mg/L, P=0.002) in the IgD group were higher than those in the non IgD group. Hemoglobin levels were lower in the IgD group [(102.3±24.0) vs (128.4±22.1) g/L, P=0.003], as well as lactate dehydrogenase [(190.1±26.0) vs (236.1±62.8) U/L, P=0.002]. A total of 8 patients in the IgD group received first-line treatment, among which 7 achieved hematological remission. Three patients in the IgD group and 5 patients in the non-IgD group died. Conclusions: The incidence rate for soft tissue involvement and dFLC level of the patients with IgD-type AL amyloidosis are higher in the IgD group. Conversely, hemoglobin levels and lactate dehydrogenase are lower.