Hamartomatous fibro-osseous metaplasia Age: 10-70; common in 2nd - 3rd decade Common locations:

◦ femur, tibia, pelvis, ribs, skull 70% monostotic

Radiography:◦ Variable: fibrous matrix- ground glass osteoid

matrix- sclerotic◦ Zone of transition narrow (sclerotic rim)

-Sclerotic lesion in femur secondary to presence of increased woven bone

-Pathologic fracture

90% unilateral 3% Albright’s Syndrome

◦ precocious puberty, café-au-lait spots, polyostotic bone lesions

Femur- Sheppard’s crook varus deformity Cherubism- expanding facial bones, sinuses Pregnancy- lesions may enlarge

Monostotic: UBC Polyostotic: Ollier’s disease, mets Rib lesions: EG, Ewing’s, mets Skull base: meningioma- skull base

hyperostosis, Paget’s

-Differential Dx: UBC- FD may appear very cystic on MR

-UBC cold on bone scan; FD- warm

Occurs only in the tibia and fibula Infants and children X-ray: mixed lucent/sclerotic, thickened

cortex (anterolateral), anterior bowing, synchronous tibia/fibula

DDX: adamantinoma (epithelial nature)◦ slightly older age >20

Epiphyseal lesion Age: <30 (growth plate usually open) X-ray: epiphysis, lytic destructive lesion,

centrally located, usually extends into metaphysis,

DDX: CIGG – chondroblastoma, infection, GCT, intraosseous ganglion,

DDX: EG, ABC, mets, myeloma

T1

T2

T1 GAD

PF: S.T. mass with vascular calcifications MRI: T1:

◦ Lacy high signal within lesion represents fat within lesion

◦ T2 and T1 post Gad: tortuous vascular channels possible phleboliths

◦ Most common S.T. mass of childhood; intramuscular; size may vary throughout the day

Primary small cell bone neoplasm Derived from reticulocyte- occurs in areas of

red marrow; long bones, axial skeleton Diaphyseal- older; Metaphyseal younger Age: 1st –2nd decade; 96% Caucasian

Radiography◦ Highly aggressive tumor; permeative pattern◦ Medullary tumor; infiltrative; periosteal reaction-

spiculated, lamellated- many layers present◦ No mineralized matrix◦ S.T. mass common◦ DDX: EG, lymphoma, OS, infection

Typically metastatic to bone; common tumor in childhood

In childhood- acute leukemia, ◦ lymphocytic or undifferentiated

50% of children have osseous involvement at time of DX, and 70-80% during disease

Childhood radiographic changes◦ Radiolucent metaphyseal bands- growth arrest

disturbance; not leukemic infiltrate- involve areas of rapid growth

◦ Diffuse osteopenia- often the only finding◦ Periosteal reaction- lamellated◦ Osteolytic lesions- permeative/ moth eaten◦ Sclerotic lesions

One of the most common bone tumors Almost always in long bones (femur, tibia) Age: Usually > 2 y.o. and < 20 y.o. Histo: fibroblasts and giant cells Usually regress with age; rarely seen in 30’s Usually an incidental finding

Radiography◦ Unilateral or bilateral◦ Osteolytic lesion; well defined; sclerotic margin;

oval, scalloped, lobulated, eccentric, ◦ Metadiaphyseal, cortically based, ◦ Periosteal reaction absent- unless path fracture◦ Femur: posteromedial; healing begins in

diaphyseal region

Jaffe-Campanacci Syndrome◦ Multiple NOFs◦ Café-au-lait spots◦ Mental retardation

precocious puberty, hypogonadism, cryptorchidism, ocular anomalies, cardiovascular anamolies

T1

T2

T1 GAD

Uncommon: long bones, spine, hands, feet, pelvis, shoulder

Age: 5- 20 y.o. Usually metaphyseal Highly vascular expansile lesion; multiple

cavities- filled with blood Primary or secondary lesion; solid

component

Radiography◦ Expansile, geographic lytic lesion; eccentric◦ Usually metaphyseal◦ Margin- sharp, nonsclerotic; outer margin thinned,

may be imperceptible radiographically◦ MRI/ CT fluid-fluid levels◦ DDX: UBC, NOF, FD, Osteoblastoma- spine,

Telangiectatic osteosarcoma

Long bones- (prox humerus/ femur) metaphyseal- move toward diaphysis with bone growth

Age: 1st two decades of life Bone cyst- serosanguineous fluid Bony septations Pathologic fractures 2/3’s of cases

Radiography◦ Well-defined lytic lesion- central in medullary

space; bone expansion, sharp margin◦ Periosteal reaction only in presence of path

fracture- “fallen fragment sign”◦ Radiolucent with trabeculation◦ DDX: FD, ABC, NOF

Nonneoplastic lesion of bone (reticulohistiocytosis)

Usually solitary- EG◦ Multiple- Hand-Schuller-Christian◦ Systemic- Letterer-Siwe◦ Long bones, skull, spine, ribs, pelvis◦ Age: 1st two decades (5 – 10 y.o.)

Radiography◦ Variable: osteolytic oval, slow growing lesion

occasionally aggressive appearing◦ Medullary space; centrally located◦ Periosteal reaction – 10% of cases◦ Nucs scan – negative 1/3 of cases

Metaphyseal- epiphyseal lesion; long bones Age: 20 - 50 y.o. (growth plate closed) rare

under age 15 y.o. Progressive potentially malignant lesion Histo: Giant cells and mononuclear spindle

shaped cells

Radiography◦ Lytic lesion; arises in metaphysis and extends into

epiphysis; growth plate closed◦ Well defined, nonsclerotic margin, abuts articular

surface, eccentric, usually large (> 4-6cm) ◦ Radiographic appearance does not help in

determining if benign or malignant

Exostosis; bony projection with a cap of hyaline cartilage; aberrant cartilage

Metaphyseal, points away from joint; long bones, around knee

Age: 2nd decade; growth stops when growth plate closes

Single or multiple; sessile, pedunculated Malignant potential; increase with multiple

lesions

Radiography◦ Bony projection; contiguous medullary space and

cortex; overlying cartilage cap◦ Pedunculated/ sessile◦ Pain- malignant transformation/ mechanical

problems, bursa formation◦ Cartilage cap; normally < 1-2 cm

DDX: ◦ Single lesion: Parosteal osteosarcoma (no

continuity of medullary space and cortex)◦ Multiple: Enchondromatosis; FD◦ Malignant Transformation: Chondrosarcoma;

Pain; Growth after growth plate closes Cartilaginous cap > 2cm thick

T1

T2

T1 GAD

Similar to osteoblastoma; < 2 cm in size Femur/ tibia/ bones of the hands/ feet/

spine Usually cortical;Fibrovascular nidus (<

1cm); adjacent reactive bony sclerosis Night pain relieved by aspirin Age: < 25 y.o.

Radiography◦ Round/ oval radiolucency (nidus <1-2cm)◦ Cortically located◦ Thick adjacent bony sclerosis

Nucs: “Target” sign; MR: Nidus- bright on T2 with marked enhancement with Gad; CT used to identify the nidus

DDX: stress fracture, osteomyelitis

Malignant bone tumor that forms osteoid tissue

Most common primary malignant bone tumor other than multiple myeloma

Involves areas of active growth; Metaphysis; femur, humerus, tibia, pelvis

Age: 2nd decade

Radiography◦ Aggressive tumor; lytic (permeative)/ sclerotic

(amorphous, cloudlike)/ mixed◦ Periosteal reaction: lamellated, spiculated◦ Large S.T. mass; skip lesions (MRI)

Subtypes◦ Telangiectatic: (<20y.o.) Lytic, expansile,

aggressive, may mimic ABC radiographically◦ Parosteal: (2nd-5th decades) low grade, better

prognosis, stuck on appearance post femur◦ Periosteal: (20 y.o.) Surface OS, aggressive,

better prognosis than conventional OS; tibia◦ Multicentric: synchronous lesions, poor prognosis;

sclerotic lesions; children

Synovial metaplasia; multiple osseous/ cartilaginous intraarticular loose bodies

Nourished by synovial fluid Limited ROM/ pain DDX: PVNS, loose bodies DJD Monoarticular; knee, hip, shoulder, elbow

Radiography◦ Effusion present; abnormal calcifications◦ Ossified loose bodies seen on plain film◦ Cartilaginous loose bodies seen on MR ◦ Secondary OA◦ Pressure erosive changes