Summary:A 35-year-old woman diagnosed with multiple myeloma (IgG, type, stage IIIA) received an autologous peripheral blood stem cell transplant (PBSCT). She was euthyroid without autoreactive antibodies prior to the transplant. The patient complained of malaise, weight loss and low grade fever 1 month after transplant, despite rapid haematopoietic recovery. Thyroid function tests on day 34 revealed hyperthyroidism associated with anti-thyroid peroxidase antibody. Antinuclear antibody was also detected, and platelet-associated immunoglobulin was increased. These findings disappeared spontaneously by day 62 without treatment. Autoimmune diseases may occur transiently after autologous PBSCT. Keywords: autoimmune; autologous; peripheral blood stem cells; transplantation; multiple myeloma Stem cell transplantation has been used increasingly for the treatment of multiple myeloma, especially in patients with favorable performance status and adequate organ function. 1 High-dose chemoradiotherapy followed by stem cell transplant has been reported to improve both relapse-free survival and overall survival in myeloma when compared to conventional chemotherapy alone. 1 Allogeneic bone marrow transplantation (BMT) appears superior to autologous BMT or autologous peripheral blood stem cell transplantation (PBSCT) because of a decreased incidence of relapse. However, transplant-related morbidity and mortality is a major concern with allogeneic BMT. Autologous PBSCT has several advantages over allogeneic BMT, including rapid engraftment and low transplant-related mortality. However, immunologic abnormalities, such as generation of autoreactive antibodies, have been reported in the setting of autologous BMT or PBSCT, similar to allogeneic BMT. 2,3 We describe a case of autoimmune thyroiditis following autologous PBSCT and discuss the clinical significance of this phenomenon.
Case reportA 35-year-old woman was diagnosed with multiple myeloma (IgG, type, stage IIIA) by the presence of an M protein in the serum and marked proliferation of myeloma cells (77% of nucleated cells) in the bone marrow. Autoreactive antibodies, including thyroid receptor stimulating antibody, thyroid stimulating hormone (TSH) receptor blocking antibody, TSH receptor stimulating antibody, thyroid peroxidase antibody, and antinuclear antibody were not detected prior to therapy. Two courses of chemotherapy consisting of vincristine, melphalan, ranimustine and dexamethasone led to a marked response, reducing myeloma cells in the bone marrow from 77 to 4.8% and serum 2 microglobulin from 4.4 g/ml to 2.4 g/ml. The favorable chemosensitivity and performance status of this patient prompted us to perform an autologous PBSCT. Peripheral blood stem cells (PBSC) were mobilized with cyclophosphamide 2 g/m 2 /day for 2 days, followed by G-CSF 150 g/day; 8.1 × 10 6 CD34-positive cells per kg were collected during recovery. Conditioning consisted of hyperfractionated total body irradiation (TBI) at a dose of 13.2 Gy and melphalan 180 mg/m 2 . Unpurged PBSC were reinfu...