Cotton-wool skull appearance on imaging is most characteristic of which disease?

Cotton-wool skull appearance on imaging is most characteristic of which disease?

• A. Osteoporosis
• B. Osteoarthritis
• C. Paget disease
• D. Fibrous dysplasia

Answer: (C)

Cotton-wool appearance on skull imaging comes from patchy, irregular sclerosis produced by abnormal bone remodeling, which is classic for Paget disease of bone. In Paget’s, bone turnover is high and disorganized, leading the skull to become thickened with fluffy, radiopaque patches that create that cotton-wool look on radiographs. This contrasts with osteoporosis, where imaging shows generalized bone loss and decreased density rather than focal sclerotic patches; osteoarthritis mainly affects joints with narrowing, osteophytes, and subchondral changes rather than the skull; and fibrous dysplasia produces a ground-glass, expansile deformity rather than the cotton-wool mosaic pattern.

Cotton-wool appearance on skull imaging comes from patchy, irregular sclerosis produced by abnormal bone remodeling, which is classic for Paget disease of bone. In Paget’s, bone turnover is high and disorganized, leading the skull to become thickened with fluffy, radiopaque patches that create that cotton-wool look on radiographs. This contrasts with osteoporosis, where imaging shows generalized bone loss and decreased density rather than focal sclerotic patches; osteoarthritis mainly affects joints with narrowing, osteophytes, and subchondral changes rather than the skull; and fibrous dysplasia produces a ground-glass, expansile deformity rather than the cotton-wool mosaic pattern.