We present the clinical and magnetic resonance imaging findings of a patien
t who, following treatment for pancreatic non-Hodgkin's lymphoma (NHL), rel
apsed with apparently isolated involvement of the right masticator space an
d left psoas muscles. Non-Hodgkin's lymphoma arising from the masticator sp
ace muscles is very rare. In addition, simultaneous lymphomatous involvemen
t of multiple discrete skeletal muscle sites, in the absence of disease els
ewhere, has previously only been reported in the limb or limb girdle muscle
s. Lymphoma should be considered as a cause of isolated enlarged skeletal m
uscles, even when involving such distant sites.