The findings in this case are typical of Madelung disease, with bilaterally symmetric, non-encapuslated fatty masses in the posterior neck. Other differential diagnoses to consider in the case of multiple lipomatous lesions would include Dercum disease, familial multiple lipomatosis and Bannayan-Zonana syndrome. 

The cystic lesion in the right side of the neck is typical of a sebaceous cyst, however an epidermal inclusion cyst cannot be excluded as it would look identical.