Department of Haematology, Royal Free Hospital, London, UK.
A 46-year-old-man received high dose chemotherapy and an autologous stem-cell transplant for multiple plasmacytoma. He had a prolonged period of pancytopenia post-transplantation, which was thought to be due to a suboptimal dose of transplanted stem cells in combination with the effects of interferon therapy and an altered bone marrow microenvironment. Twenty-eight months after the transplant he was found to be hyperthyroid. Anti-thyroid therapy has led to a sustained improvement in his pancytopenia.