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B. J. Manaster, MD, PhD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Osteonecrosis (AVN)
Renal Osteodystrophy
Less Common
Cement & Bone Fillers, Normal
Neoplasm
Chondroblastoma
Ewing Sarcoma
Osteosarcoma, Conventional
Legg-Calvé-Perthes (LCP)
Osteopoikilosis
Osteopetrosis
Pycnodysostosis
Rare but Important
Down Syndrome (Trisomy 21)
Hypopituitarism
Hypothyroidism
Turner Syndrome
Morquio Syndrome
Thiemann Disease
Deprivation Dwarfism
Multiple Epiphyseal Dysplasia
Trichorhinophalangeal Dysplasia
Seckel Syndrome
Lesch-Nyhan
Idiopathic Hypercalcemia
Homocystinuria
Complications of Fluoride
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Differentiate between extent of sclerosis
Focal, isolated to epiphysis
Osteonecrosis
Chondroblastoma
Legg-Calvé-Perthes
Epiphyseal/metaphyseal
Ewing sarcoma
Chondrosarcoma
Osteopoikilosis
Diffuse
Renal osteodystrophy
Osteopetrosis
Pycnodysostosis
All diagnoses listed as “rare but important”
Helpful Clues for Common Diagnoses
Osteonecrosis (AVN)
Sclerosis is secondary to surrounding osteopenia (relative sclerosis)
Classic appearance is central sclerosis in femoral head
Later, sclerosis is secondary to osseous impaction from collapse
Even later, sclerosis is due to reparative bone formation
Renal Osteodystrophy
Diffuse sclerosis, including epiphyses
May be part of primary disease, due to activation of osteoblasts
More prominent, as neostosis, when undergoing effective treatment
Indistinct trabeculae
Other signs of renal osteodystrophy
Rickets: Widened zone of provisional calcification, frayed metaphyses
Hyperparathyroidism: Resorption patterns (subperiosteal, endosteal, subchondral, subligamentous)
Soft tissue calcification
Helpful Clues for Less Common Diagnoses
Cement & Bone Fillers, Normal
Commonly used to fill lesion sites following curettage
Most common lesion in epiphyseal region treated this way is giant cell tumor
Cement: Homogeneous, more dense than cortical bone
Nonstructural bone graft: Round or square pieces, same density as cortical bone
As it incorporates, approaches normal bone density
Rare use of coral as structure with haversian canal-like morphology to allow substitution by normal bone
Neoplasm
Chondroblastoma
Most common epiphyseal neoplasm
Generally arise in skeletally immature (teenage, young adult) patients
Margin generally sclerotic
May contain chondroid matrix, resulting in greater sclerosis
Often elicits dense periosteal reaction
Ewing Sarcoma
Generally metadiaphyseal lesion, but may cross into epiphysis (physis is only a relative barrier)
Age range: 5-30 years
Lesion generally is highly aggressive, with permeative destruction, cortical breakthrough, and soft tissue mass
Rarely may be more indolent, remaining contained for variable amount of time
Elicits significant osseous reaction, in form of new bone formation; this is source of sclerosis
Osteosarcoma, Conventional
Generally metaphyseal in location but may cross into epiphysis
Highly aggressive lesion, with permeative bone destruction, cortical breakthrough, soft tissue mass
Tumor osteoid results in amorphous sclerosis, both in bone and in soft tissue mass
Legg-Calvé-Perthes (LCP)
Osteonecrosis of femoral head in child
Age 4-8 most common
Early sign: Sclerosis of femoral head
Later signs
Fragmentation of femoral head
Flattening of femoral head
Late appearance
Coxa magna deformity (short, broad femoral head and neck)
Early development of osteoarthritis
Osteopoikilosis
Round, regular, generally subcentimeter sclerotic lesions
Bone islands (hamartoma)
Epiphyseal and metaphyseal
Generally bilaterally symmetric
1 of sclerosing dysplasias
Incidental finding
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