Ferritin and lactoferrin are found in increased concentration in tumors. Increased extracellular fluid coupled with increased capillary permeability in tumors may also increase localization. Therefore, lymphoma's avidity for gallium is related to its histopathology. This patient's symmetric muscle involvement is unusual. The clinical findings of bilateral, symmetric muscle weakness are typically used to differentiate polymyositis from other muscular diseases that would include pyomyositis and lymphoma.
Tropical myositis is characterized by bacterial infection with staphylococcus aureus.
At imaging, pyomyositis often manifests as rim-enhancing fluid collections. Several reports have also shown the preferential uptake of Ga-67 in tropical myositis that involved major muscle groups. However, in our patient, lack of increase in creatine kinase enzyme and bone marrow biopsy proved conclusive and obviated further work-up. We have presented an unusual case of symmetric, diffuse muscle gallium uptake due to lymphomatous infiltration of muscle. This atypical gallium distribution may be mistaken for more common presentations of muscle diseases such as rhabdomyolysis.