Explanation
Subperiosteal resorption, particularly classically located on the radial aspect of the middle phalanges of the index and middle fingers, is pathognomonic for hyperparathyroidism. 'Picture frame' vertebrae and 'cotton wool' skull are seen in Paget's disease, while an 'Erlenmeyer flask' deformity is associated with Gaucher disease and osteopetrosis. Reference: Apley & Solomon's System of Orthopaedics and Trauma, 10th Edition.