Paget's Disease (Osteitis Deformans)
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Paget's Disease (Osteitis Deformans)
What is it?
Paget's disease is a chronic progressive focal disease of bone,
characterized by excessive resorption followed by excessive formation
of bone, with abnormal bone remodeling.
This process results in mosaic pattern of lamellar bone, with
extensive local vascularity and increased fibrous tissue in the bone
Involvement is usually polyostotic and asymmetric, and prefers the pelvis, spine, skull, femur, and tibia.
1) "hot" or "active" phase (osteolytic dominant, with fibrous replacement of marrow and vascular hypertrophy);
2) "mixed" phase (disorganized lamellar bone deposition plus osteolysis; rapid bone turnover);
3) "cold" phase (osteoblastic dominant; pagetoid woven bone replaced
by islands of lamellar bone, but haversian systems and remodeling along
lines of stress do not occur).
Who gets it and why?
Hard to accurately say who is affected because many affected
individuals are asymptomatic, but autopsy studies have shown
approximately 3% of adults over 40 have the disease.
Unusual under age 40.
Unknown etiology, probably viral.
Clinical Findings:Often asymptomatic, but can have a painful, warm extremity, bowing of
long bones, high output CHF, enlarged hat size, sequelae from spinal
cord/nerve compression, and elevated serum alkaline phosphatase and
Plain films: Lysis typically begins at an epiphysis and slowly
advances at rate of a few mm per year to involve entire bone.
Classically described as a "candle flame" or "blade of grass" lesion,
with lucent osteolytic advancing edge, and sharp transition between
normal and involved bone.
Pagetoid (woven) bone forms behind advancing osteolysis, with
coarsened trabeculae and overall decreased cortical density. Not
uncommon to see insufficiency fractures and deformities because of lack
of bone remodeling.
Spine: Classic lesion is the "picture frame" appearance of the
vertebral body, with initial widening of the peripheral cortex. This
progesses to a dense sclerotic body with continued endosteal
progression, and eventually even the posterior elements are involved.
Skull: Commonly involves cranial vault. Well demarcated geographic
appearance ("osteoporosis circumscripta") in lytic phase (particularly
frontal bones), followed by focal radiodensities with pagetoid bone
formation, and finally a thickened radiodense "cotton wool" appearance
in the quiescent phase. Basilar invagination can be seen due to
insufficiency of the pagetoid bone; subsequent narrowing of neural
foramina and foramen magnum can occur.
Pelvis: Thickening of the iliopubic and ilioischial lines early in
the disease, with subsequent trabecular thickening and acetabular
Long bones: Cortical thickening and bone enlargement. Bowing of tibia and femur.
CT: Can demonstrate dense enhancement of very vascular lesions in the
lytic phase. Cortical thickening and typical "swiss cheese" appearance
of bone are also well demonstrated.
-Helpful in determining extent of disease.
-Extremely hot in lytic phese; can be cold if inactive (uncommon).
-Increased radiotracer uptake usually abuts on joint and extends distally.
Fractures: Secondary to insufficiency, often incomplete.
Neoplasm: Sarcomatous degeneration is rare (<1%), but more likely with extensive disease.
Main consideration is metastatic disease, which much more commonly involves ribs than Paget's.
Goal is to arrest the osteolytic process.
1) Calcitonin (inhibits bone resorption)
2) Disphosphonates (inhibit demineralization)
3) Mithromicin (cytotoxic antibiotic)
1. Metabolic Bone Disease and Clinically Related Disorders, Third Edition. Avioli, L and Krane, S, Eds. c 1998, Academic Press, San Diego, CA. pp 545-596.
2. Musculoskeletal Imaging- The Core Curriculum Serie . Chew, F. c 2003, Lippincott, Williams & Wilkins, Philadelphia, PA. pp 478-484.
3. Primer of Diagnostic Imaging, Second Edition. Weissleder, R, Rieumont, M, and Wittenberg, J. c 1997, Mosby, St. Louis, MO. pp 428-9.
Several photographs are courtesy of Dr. Hunter and Dr. Richardson's web sites.