Fibrodysplasia ossificans progressiva (FOP) is a severe, progressive disease of 
the musculoskeletal system. Muscles, tendons and other connective tissues ossify 
after minor trauma, and patients often become encased in a second immobile 
skeleton. There is no known cure or treatment for FOP. It has been found that 
lymphocytes from FOP patients elaborate excess levels of bone morphogenic 
protein-4 (BMP-4). Given this, it has been suggested that allogenic bone marrow 
transplantation (BMT) possibly could be a cure for FOP, and drawn attention to a 
previously unappreciated case of an FOP patient who had successful BMT for 
aplastic anemia with apparent short- and medium-term arresting of the FOP 
disease process. However, BMT has non-trivial associated morbidity and 
mortality. Here, it is noted that if B cells are found to be the lymphocytes 
responsible for excess BMP-4 production in FOP, use of Rituximab, a monoclonal 
anti-CD20 antibody which effectively targets B cells, could be a less permanent 
and less risky treatment alternative for FOP.