Abstract: Objective To analyze the MRI manifestation and clinical data of primary musculo-soft tissue lymphoma and improve the diagnosis of this disease.Methods All lymphoma patients who were admitted to Xuzhou Cancer Hospital from June 2015 to October 2021 were included in this study and their imaging and clinical data were retrospectively analyzed. Finally, four patients with primary musculo-soft tissue lymphoma were included. MRI images of the lesions were blindly read by two associate chief physicians from our imaging department. In case of disagreement, the opinion after negotiation was adopted.Results There were three men and one woman among the four patients, with an average age of 56 years. The lesions were located in the upper extremities in 1 case and in the lower extremities in 3 cases. The lesions were hard with slight pain and poor sliding by palpation. No redness, swelling and heat were found on the skin. No enlarged lymph nodes and hepatosplenomegaly were seen in all patients with negative laboratory examination results. The MRI findings were basically the same: the lesions showed uniform iso-intensity T1 and slightly longer T2 signal shadows, with limited diffusion, heterogeneous hyperintensity on T2WI and PDWI images, with uneven and slightly enhanced enhancement. There was no clear boundary between the lesion and the adjacent soft tissues. Some muscle fibers, blood vessels and nerves were wrapped, but their distribution, morphology and strengthening were not abnormal. The soft tissue surrounding the lesions had no/mild edema, without structural distortion. The bone adjacent to the lesions was not abnormal.Conclusions Primary muscle-soft tissue lymphoma has certain morphological characteristics of MRI, which combined with the absence of systemic lymph node enlargement and hepatosplenomegaly can further improve the diagnosis of primary muscle-soft tissue lymphoma.