The diffuse neurofibroma is an uncommon subtype of neurofibroma that has received little attention in the imaging literature. Most common in ages 10-30, in males and females, with a slight predilection for the trunk, then head and neck, then limbs. May become very large, but very rarely undergo malignant transformation. Treatment of diffuse neurofibromas (not associated with NF1) is often surgical resection. Complete resection is often difficult because of the extensive and infiltrative nature of many of these lesions. To our knowledge, the diffuse neurofibroma has been reported extremely rarely within the shoulder girdle. In this report, we presented an adult patient, without NF1 diagnosed, who developed invalidate status of left upper limb due to a giant diffuse neurofibroma involving the left brachial plexus, with a high growth diffuse pattern and plexiform architecture imagistic, grossly and without results at both surgical interventions. The diagnosed was by MRI and sonographic imaging and histopathologic examination. His immediately survival perspective was not affected but the functionality of the left upper limb was severe reduced.