An 80-year-old woman presented to the hospital with a 11-month history of swelling that progressively involved the whole left upper limb. Her clinical history was rilevant for arterial hypertension, obesity and rheumatoid arthritis. Ultrasonography revealed hypoechoic nodules in soft tissue of the left arm,brachial vein thrombosisandmalignant left axillary lymphadenopathy. The patient started antithrombotic therapy and underwent axillary lymph nodes excisional biopsy: a diagnosis of diffuse large B-cell lymphoma was made and she was referred to hematology clinic for chemotherapy. At a 3-month follow-up visit, the patient showed decrease of the swelling of her upper limb; the ultrasonographic control demonstrated reduction in size and number of soft tissue nodules and resolution of vein thrombosis.