Hump behind the shoulders is a lump of fat on the back of the neck.
A hump behind the shoulders by itself is not a sign of any one, specific condition. The doctor must consider this along with other symptoms and test results.
Osteoporosis may cause a curvature of the spine in the neck called kyphoscoliosis.
Young WF. The incidentally discovered adrenal mass. N Engl J Med. 2007; 356:601-610.