Diffuse F-18 FDG uptake in skeletal muscles secondary to chills resulting from sepsis: A cause for underestimation of viable tumor

FDG PET was performed on a 42-year-old male patient with B-cell, low-grade follicular non-Hodgkin lymphoma to evaluate the response to chemotherapy. The bone marrow lesions appeared to have improved compared with the prior PET scan, but there was intense skeletal muscle FDG uptake. Repeated scanning performed after 1 week revealed an increase in the size and intensity of bone marrow lesions compared with the pretherapy study, suggesting worsening. The authors present this case of generalized intense skeletal muscle uptake secondary to chills resulting from sepsis causing a falsely reduced tumor-to-normal tissue ratio.