Joint manifestations in myelodysplastic syndromes. A report of three cases presenting as polymyalgia rheumatica.

We report three cases of polymyalgia rheumatica occurring after (n = 1) or shortly before (n = 2) a diagnosis of myelodysplastic syndrome. These cases demonstrate that: 1) inflammation and bleeding are not the only causes of anemia in patients with inflammatory joint disease; 2) side effects of drugs, Felty's syndrome and large granular lymphocyte expansion are not the only causes of neutropenia in this setting; 3) lymphomas and monoclonal gammopathies are not the only hematologic diseases that can present under the guise of polymyalgia rheumatica; 4) a high index of suspicion for a myelopoietic disorder should be maintained in patients who have not only joint symptoms and cytopenia, but also vasculitis, neurologic symptoms, thyroid disorders or protein electrophoresis abnormalities. Because myelodysplastic syndromes are due to clonal proliferation of abnormal stem cells, our cases are in line with recent investigations suggesting that abnormalities of bone marrow stem cells are involved in the pathogenesis of some inflammatory joint diseases. Studies of the clonality and karyotype of synovial cells from affected joints might lend further support to this hypothesis.