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Aneurysmal Bone Cyst 
Calcaneal Cyst 
Chondroblastoma 
Chondrosarcoma Rib 
Fibrous Dysplasia Hip 
Pigmented Villonodular Synovitis 
Solitary Bone Cyst 
Synovial Sarcoma 
- Nomenclature:
- Osteoid: organic molecules that form non-mineralized matrix
- Bone Structure:
- Cortex:
- Periosteum: (2 layers of cells, inner having osteoproductive
potential)
- Benign periostitis
- Thick, wavyform, uniform
- Causes => venous stasis, ischemia, hypertrophic
pulmonary osteoarthropathy, thyroid acropachy
- Haversian: (central blood vessel in haversian canal)
Osteoblasts and osteoclasts change periosteum into haversian bone.
- Endosteum: Thin layer of inner portion between haversian
system
and trabecula restructures haversian system into trabecular system.
- Cancellous = trabecular bone
- Bone marrow = hematopoietic and stroma (adipocytes from same
precursor as osteoblasts)
- Bone Lesions:
- Agressiveness:
- Expansile with sclerosis: slow growing
- Non-expansile, no sclerosis: aggressive
- Malignancy: wide transition zone, cortical destruction,
periosteal reaction
- Benign vs. malignant
- Cortical destruction or thinning in benign: infection, EG,
ABC, fibrous and cartilaginous lesions.
- Periostitis
- Benign = thick, dense, wavy
- Malignant =
lamellated
(onion-skinned), amorphous, sunburst.
- EG, ABC, OO, trauma can look
malignant. If looks benign, likely to be benign.
- Normal periosteal reaction occurs in infants 2-6 months of
age.
- Zone of transition: narrow vs. wide. Sclerotic is narrow.
Permeative is wide (Round cell = MM, reticulum cell sarcoma (bone
lymphoma), Ewing's). Other permeative is infection and EG. Aggressive
not necessarily malignant.
- Benign by age
- <30: Cystic: EG, ABC, NOF, chondroblastoma, solitary
bone
cyst; Osteosclerotic: osteoid osteoma, osteoblastoma
- Malignant by age:
- 1-30: Ewing's sarcoma, osteosarcoma
- 30-40: GCT, parosteal sarcoma, fibrosarcoma, MFH, reticulum
cell sarcoma
- >40: Chondrosarcoma, metastatic disease, myeloma
- Lytic lesion, old patient (MMOL):
multiple myeloma, mets, osteosarcoma, lymphoma
- By osseous site:
- Epiphyseal
- Peds (ICE)
- Infection
- Chondroblastoma
- EG
- Adults (GMC-C)
- GCT
- Metastasis
- Cysts (ganglion, subchondral, geodes)
- Clear cell chondrosarcoma
- Metaphysis
- High-grade osteosarcoma
- Osteoblastoma
- Chondromyxoid fibroma
- Osteochondroma
- Metaphyseal enlargement (Ehrlenmeyer
flask deformity)
- Metadiaphysis
- Peds
- Benign cortical defect/NOF
- Diaphysis malignant round cell (40% of Ewing's), fibrous
dysplasia, NOF, simple cyst, ABC, 75% of osteoblastomas
- Metastases
- Ewings sarcoma
- Chondrosarcoma
- By Bone:
- Tibia: Adamantinoma, juvenile adamantinoma (ossifying
fibroma), 28% of chondromyxoid fibroma, osteofibrous dysplasia.
- Femur and tibia: osteoid osteoma
- Posterior femur: parosteal osteosarcoma, cortical desmoid
(avulsion injury)
- Post vertebral elements: osteoblastoma
- Calvarium, vertebra, jaws: hemangioma
- Mandible and maxilla: ameloblastoma
- Sacrum:
- GCT
- ABC
- Osteoblastoma
- Hemangioma
- Osteochondroma
- Chordoma
- MM
- Lymphoma
- Ewing (PNET)
- Chondrosarcoma
- Osteosarcoma
- Angiosarcoma
- Lytic:
- Benign (FENGOMASCHIC):
- <30: EG, ABC, NOF, chondroblastoma, solitary bone cyst
- Epiphyseal: Chondroblastoma, GCT, infection, Geode, (EG,
ABC)
- No periostitis
- Fibrous dysplasia
- Enchondroma
- NOF
- Solitary bone cyst
- No calcifications on plain films (lipoma calcifies)
- Multiple: Fibrous dysplasia, EG, enchondroma, high PTH,
infection, (mets, myeloma)
- Rib lesions: fibrous dysplasia, ABC, enchondroma, EG,
(mets, myeloma)
- Malignant: Mets, Myeloma
- Matrix:
- Osteoid matrix.
- Benign (OBOOO)
- Osteoma
- Usually found in calvaria and paranasal sinuses
- Bone island (enostosis)
- Osteopoikilosis - multiple bone islands clustered
around joints.
- Osteoid Osteoma
- Cortex of tubular bones is most common location
- Nidus is composed of highly vascular fibrous tissue,
osteoid and immature bone
- Sclerotic reaction
- Maybe away from the lesion if nidus is
intraarticular, similar to remote periosteal reaction in
chondroblastoma (no periosteum in the joints)
- Osteoblastoma
- Similar to osteoid osteoma, but nidus measures > 2cm
- May rarely undergo malignant transformation
- Ossifying fibroma
- Found in anterior proximal tibia
- Diff Dx
- Adamantimoma
- Cortical fibrous dysplasia
- Malignant
- Osteosarcomas
- Conventional (central)
- Telangiectatic
- Fluid-fluid levels
- Parosteal (surface)
- Found in posterior distal femoral metaphysis,
proximal tibia or proximal humerus
- Cleavage plane between tumor and adjacent bone is
usually seen
- Periosteal (surface)
- Usually diaphyseal in location
- Causes scalloping
- Soft tissue osteosarcoma
- Cartilaginous
- Enchondroma (arcs and rings calcifications)
- Ollier's disease
- Mafucci's syndrome
- Osteochondroma (exostosis)
- Multiple hereditary osteochondromas
- Dysplasia epiphysealis hemimelica (Trevor disease)
- Intra-articular epiphyseal osteochondromas
- Juxtacortical chondroma
- DiffDx: periosteal osteosarcoma
- Chonroblastoma
- Found exclusively in the epiphysis with open physis
- In older patients, clear cell chondrosarcoma should be
considered
- Chonromyxoid fibroma
- Chondrosarcoma
- Fibrous
- Fibrous dysplasia
- Long ground glass lesion in a long bone
- McCune-Albright syndrome
- Coast of Maine
- Hormonal disorder
- Fibrous cortical defect/NOF
- Bubbly lytic cortical lesion with sclerotic margin
- Malignant fibrous histiocytoma
- Can involve soft tissue or bone
- Marrow and mets
- Ewing's sarcoma
- Most are lytic (permeative)
- May have some reactive bony sclerosis (onion-skin
periostitis, but can be sunburst or amorphous)
- Soft tissue component is not calcified
- Primary Lymphoma
- Multiple myeloma
- Mets
- Lytic: Lung, kidney, breast, thyroid, GI, neuroblastoma
- Blastic: Prostate, breast, bladder, GI, lung,
medulloblastoma
- Vascular
- Benign: Hemangioma, lymphangioma, glomus tumor
- Malignant: Angiosarcoma
- Miscellaneous
- Peripheral nerve sheath tumors
- Morton's neuroma
- Giant cell tumor of tendon sheath
- Synovial cell sarcoma
- Giant cell tumor (osteoclastoma)
- Occur after epiphyseal closure
- Originates in metaphyses and extends into epiphyses
- Solitary bone cyst
- Fallen fragment sign
- ABC
- LCH
- Vertebra plana
- Brown tumor of hyperparathyroidism
- Local accumulations of osteoclasts
- Myositis ossificans
- Matures in the periphery first (paraosteal osteosarcoma
shows denser calcification in the center)
- Chordoma
- Adamantinoma
- Ganglion cyst
- Loculated collections of viscous fluid
- Diffuse osteosclerosis
- Short list (3MSPROF)
- Myelofibrosis
- Mastocytosis
- Metastasis
- Sickle Cell Disease
- Pyknodysostosis
- Renal osteodystrophy
- Osteopetrosis
- Fluorosis
- Long List
- Metastases
- Myelofibrosis
- Mastocytosis
- Melorheostosis
- Thickened cortical bone
- Wax on a candle appearance
- Pyknodysostosis
- Paget
- Phosphorus poisoning
- Renal osteodystrophy
- Sickle cell disease
- Tuberous sclerosis
- Osteopetrosis
- Fluorosis
- Hypervitaminosis D
- Hypothyroidism
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