OUTLINE
I.
General Principles
II.
Benign Bone Neoplasms
1.
Benign Fibrous Lesions
2.
Unicameral Bone Cyst
3.
Giant Cell Tumor
4.
Benign Osseous Tumor
5.
Benign Cartilagenous Tumors
III.
Malignant Bone Neoplasms
1.
Metastatic Carcinoma
2.
Multiple Myeloma
3.
Ewing’s Sarcoma
4.
Osteogenic Sarcoma
5.
Chrondrosarcoma
IV.
Benign Soft Tissue Tumors
1.
Lipoma
2.
Hemangioma
3.
Neurilemmoma
4.
Neurofibroma
V.
Malignant Soft Tissue Tumors
1.
Liposarcoma
2.
Malignant Fibrous Histiocytoma
3.
Fibrosarcoma
4.
Embryonal Rhabdomyosarcoma
VI.
Sample Cases
*  - audio (in some portions, text and text have been combined)
Objectives for the Session
•
General principles in musculoskeletal tumor evaluation and treatment
•
Examples of bone and soft tissue tumors, benign and malignant

I.
GENERAL PRINCIPLES IN MUSCULOSKELETAL TUMOR EVALUATION AND
TREATMENT
1.
Step-wise Musculoskeletal Tumor Evaluation
1.
Adequate history and physical examination
2.
X-ray of lesion: always ask for an x-ray in when considering bone tumors!
3.
4.
5.
Tentative diagnosis based on age and x-rays: 90% of the time you can get a good differential Dx after x-ray!
Laboratory assessment
6.
Additional radiographic assessment (CT generally for bone, MRI for soft tissue lesions)
Biopsy (site, type, processing of tissue)
2.
History and Physical Exam
1.
Age/sex
▪
There are certain tumors more common in children while there are those seen more in the elderly, and adults.
2.
Presenting complaint: mass (May bukol)
▪
Characteristics: size, mobility, rate of growth, presence of pain, duration, location
3.
Systemic complaints and findings:
▪
Weight loss – points you towards malignancy or chronic conditions
(i.e. TB) vs benign
▪
Fever – points you towards infectious cause over neoplasms, but note that some neoplasms may present with fever
▪
Loss of appetite – points you towards chronic illnesses and cancers
▪
◦
▪
(some tumors produce cachexin and tumor-necrosis factor or
TNF, which decreases appetite)
4.
History of trauma, malignancies
▪
Certain tumors may develop due to trauma
Myositis ossificans - abnormal bone growth in muscles
Because of trauma, pluripotent cells are incited to become osteoblasts.
Most common tumor seen in the bone – secondary tumors/ metastases
3.
Considerations for Cause of Mass
1.
Neoplasm – benign or malignant

2.
Infection – e.g. abscess, TB synovitis
3.
Inflammation – inflammatory arthritides (painful masses, e.g. RA, JRA, gout)
4.
Trauma – hematoma, myositis ossificans
•
As mentioned, myositis ossificans is a condition wherein muscles respond to trauma by forming bone (calcium crystals) in muscles
•
This may cause a mass but is not considered a neoplasm; an outline of bone formation in the muscle is seen in radiographs
•
Not all masses are neoplasms!
4.
Age and Bone Tumors
Type of Tumor Peak Age Incidence
BENIGN
Osteochondroma
•
Not that uncommon
•
Bony mass appreciated near the joints
2nd decade
Osteoid osteoma
Giant cell tumor
Fibrous dysplasia
Unicameral Bone cyst
2nd decade
3rd decade
1st and 2nd decade
1st – 2nd decade
Multiple myeloma
•
Bone marrow tumor
MALIGNANT
6th and 7th decade
Chondrosarcoma (cartilage-forming malignant tumor of bone)
4th to 6th decade
Osteosarcoma (bone-forming tumor) 2nd decade
Ewing’s tumor 1st to 2nd decade
SOFT TISSUE SARCOMAS
Malignant fibrous histiocytoma 6th to 7th decades
Malignant schwannoma 4th to 6th decades
3rd to 5th decades Liposarcoma (most common in the
Philippines)
Fibrosarcoma
Synovial Sarcoma
Rhabdomyoscarcoma
3rd to 4th decades
3rd decade
Usually in children

◦
Certain tumors may be more common to particular age groups
5.
X-Ray Reading of Bone Tumor
•
7 x-ray questions are used to visualize bone lesions and assess how aggressive they are.
◦
Tie these findings to the patient’s age, and other details and more often than not, you already have a diagnosis!
◦
◦
◦
1.
Where is the lesion? Which bone? Which part of the bone?
◦
Periarticular – around the joints
◦
Epiphyseal (end of the bone), epi-metaphyseal, metaphyseal, metadiaphyseal, or diaphyseal
•
Review of parts of the bone
◦
Epiphysis – end of bones
Metaphysis – wider portion of a long bone adjacent to epiphyseal plate
Diaphysis – shaft of bone
Centric (central location) or Eccentric (other than central)
◦
◦
Cortex – osteochondroma, osteoid osteoma
Cartilage – echondroma

Figure 1 Synovial Osteochondromatosis in a 24-year-old man with hip pain. Radiograph shows multiple small, dense, punctate calcifications.

Figure 2 Synovial Chondromatosis. Proximal Humerus, epimetaphysial.
•
Synovial chondromatosis may develop due to metaplasia of synovial connective tissue.
◦
◦
Uncommon cause of loose bodies.
Biopsy shows active synovial proliferation.

Figure 3 Solitary benign pedunculated osteochondroma of the femur in a 22-year-old man with an associated fracture. Radiograph of the knee reveals a mass with marrow and cortical continuity to the underlying femur (arrowheads). The lesion points away from the knee joint and a lucent area at the base represents a fracture (arrow).
•
Osteochondromas can develop due to aberrant growth of the growth plate
◦
This is usually vertical, but some cells may decide to grow perpendicular)
◦
Pedunculation is seen as a stalk, with a cartilaginous cap
Figure 4 Myositis Ossificans (Proximal Humerus) showing peripherally mineralized myositis ossificans with a radiolucent center at 12 weeks.

Figure 5 Diagram of Common Tumor Locations.
Notes on the Bone Lesions illustrated:
•
Osteoid osteoma – typically a cortical lesion
•
Osteosarcoma – usually metaphyseal in location but can spread to the epiphysis and diaphysis
•
Enchodroma – a centric metaphyseal lesion
•
Ewing sarcoma, Myeloma (round cell tumors) – usually diaphyseal in location
•
Fibrous dysplasia – usually diaphyseal
•
Fibrous cortical defect – usually eccentric, in the metaphyseal area
•
Osteochondroma – surface lesion, usually involves the metaphysis but can also involve the epiphysis
•
Aneurysmal bone cyst – metaphyseal
•
GCT – metaphyseal

•
Emphasis was placed on knowing where tumors arise from and in what age group are they common!
•
Generally, most tumors are benign, although they often are not biopsied.
•
Childhood – Usually benign
•
Elderly – Usually malignant
•
Some tumors (giant cell tumor, well differentiated cartilaginous tumors) have borderline features
•
It is important to be aware of patient age, bone involved, area of bone involved
(epiphysis, metaphysis, diaphysis; cortex, medulla or periosteum) and radiologic appearance before making microscopic diagnosis
•
X-rays are important to define the tumor’s location and aggressiveness, and are necessary to diagnose low grade cartilaginous tumors.
•
Clinical symptoms are usually not helpful in making a diagnosis
2.
How large is the lesion? How extensive is the lesion?
•
Size is relative to the number of bones affected as well as the extent of the lesion relative to the affected bone.
•
Size is usually assessed in relation to the bone involved. Example, if half of the distal phalanx has been eaten by the tumor, even if that is relatively small in itself, it is considered a large tumor because it is compared to the bone involved which is the phalanx. A large tumor is often considered when it looks as if it is “eating up” the surrounding bone.
Figure 5 Giant cell tumor of distal radius. Large lesion involving the distal epi-metaphyseal radius can be appreciated via the large hypolucent area
3.
What is the lesion doing to the bone? Aggressive or not aggressive?

•
Geographic
◦
Easily determined were normal bone ends and the tumor begins
◦
◦
•
Moth-eaten
◦
◦
Borders are easily seen, tumor is well delineated
Less aggressive
More aggressive BUT not necessarily malignant!
Ex: osteoporosis or osteomyelitis on x-ray
◦
◦
◦
4.
What is bone doing in response?
•
Bone is a living organ and would respond to the tumor, attempting to contain the tumor via walling off
1.
Marginal sclerosis
Wherein tumor margins appear moth-eaten
Sclerosis appears whiter on imaging due to effect of thickened borders
Below is a large, epimetaphyseal tumor with geographic borders and no bone response
Figure 6 Marginal sclerosis: Non-ossifying Fibroma of Femur. The epiphysis was not involved (there is a clear border).
2.
Periosteal new bone formation/Cortical thickening
•
Cortex thickens in response to a lesion
•
Here are the differences between:
◦
Osteoid osteoma (OO) : PRIMARY BENIGN
▪
Benign, painful bone-forming neoplasm usually <1 cm, delineated central nidus.

▪
▪
◦
▪
▪
◦
▪
▪
▪
Sharply localized pain more intense at night can be relieved by
NSAIDS
Grows in highly vascularized connective tissue without evidence of inflammation
Osteoblastoma: PRIMARY BENIGN
More aggressive vs OO, dull achy pain unrelieved by NSAIDS
Most frequent in the vertebral column and long bones; LARGER
NIDUS (can grow >2cm),absent/inconspicuous surrounding area of reactive bone formation
Osteosarcoma: PRIMARY MALIGNANT
High-grade intramedullary lesion producing malignant osteoid
Multiple sites may become apparent, usually affects extremities of long bones near metaphyseal growth plates.
Most common sites are the femur, tibia, and humerus
Figure 7 Osteoid osteoma. (LEFT) X-ray of an osteoid osteoma of the thigh (femur) with increased bone formation and subtle lucency (arrow) (RIGHT) T scan of an osteoid
osteoma of the thigh (femur), a small, round lytic focus (arrow) surrounded by dense bone is demonstrated.
3.
Bone remodeling and endosteal expansion
•
Cortex is usually the part of bone that expands
•
In cases of enchondroma (a type of non-aggressive tumor), the cortex expands and bone adapts, causing the periosteum to also expand and be pushed out. This creates a NEOCORTEX

Figure 8 Osteoblastoma. The radiographic appearance of an osteoblastoma is usually of an expansile lesion eccentrically placed in the bone, frequently a vertebra, with clearly defined smooth margins. Although the margins of the tumor may expand the bone, it usually does not break the cortex.
4.
Neocorticalization
•
Cortex responds by forming new bone
▪
5.
Poorly organized periosteal new bone formation
Codman’s triangle
•
Formed by tumor, cortex and lifted periosteum; a sign of AGGRESSIVE tumor
•

Figure 9 Codman's triangle. Tumor has a triangle (Codman’s triangle) bordered by lifted periosteum, cortex and the tumor. It is formed by the elevation of the periosteal reaction.
▪
Sunburst formation
•
As seen in osteogenic sarcoma, the osteoblasts form bone around blood vessels, creating the “hair-on-end appearance”

Figure 10 “Sunburst” Osteosarcoma. Note Codman’s triangle and sunburst appearance.
•
If the lesion grows rapidly but steadily, the periosteum will not have enough time to lay down even a thin shell of bone.
In such cases, the tiny fibers that connect periosteum to the bone (Sharpey's fibers) become stretched out perpendicular to the bone.
◦
When these fibers ossify, they produce a pattern called "sunburst" or "hairon-end" periosteal reaction, depending on how much of the bone is involved by the process.
▪
Onion peel
•
Commonly seen in Erwing’s sarcoma, which is a diaphyseal round-cell tumor common in the 1st to 2nd decades of life
•
In Ewing sarcoma, onion peeling is due to osteoblast forming around periosteal blood vessels in vertical manner

Figure 11 Onion peel. Classically described in Ewing’s tumor but it is not pathognomonic
(also seen in osteomyelitis or osteogenic sarcoma)
***With rapidly growing processes, the periosteum cannot produce new bone as fast as the lesion is growing. Therefore, rather than a solid pattern of new bone formation, we see an interrupted pattern.

5.
Is there cortical erosion?
•
Is the cortex intact or not?
•
A lesion with erosion or break is more aggressive.
6.
Is there a soft tissue mass?
•
Cortex seems to be intact, but there is tumor inside and outside the bone.
Therefore is the cortex intact? A
•
Lesion may be so aggressive it just passes through bone and drills small holes through the cortex without destroying it (e.g. round cell tumor): not a good sign!
•
Lesion may proliferate slowly, as in a locally-invasive giant cell tumor: slowly eats bone and allows the body to produce new bone. However, threshold can be reached wherein bone is unable to respond, and the tumor breaks out.
•
A soft tissue mass is usually white in radiographs
7.
What is the matrix?
•
Recall stages of bone growth
1.
Osteoid – bone has formed with type I collagen, but has not mineralized
2.
Woven bone – bone has mineralized, but is not organized and still in haphazard pattern
1.
Lamellar bone – collagen fibers have already oriented themselves to form layers
•
Note: trabecular bone is also lamellar (therefore MATURE), but without Haversian canals, becoming spongy bone.
1.
Osteoid
◦
Seen in bone forming tumors such as osteogenic sarcoma
◦
Cloudy appearance
▪
▪
2.
Chondroid
•
Seen as whiter material than osteoid on imaging because it is made purely of calcium crystals
Stippled, with arcs and rings
Enchondroma – cartilage inside the bone
▪
Osteochondroma or exostosis – on bone surface
Cartilage either calcifies or ossifies
3.
Ground glass

◦
◦
◦
Seen in fibrous dysplasia affecting children and young adults
See areas of lysis and endosteal expansion
Fibrous dysplasia is not a neoplasm but an aberration in how bone is formed
◦
◦
◦
◦
Bone does not mature to lamellar bone and remains as woven bone in a matrix of fibrous tissue, therefore it is weaker than normal
Histopathology: spicules of lamellar bone in a fibrous background
Imaging: ground-glass or glazed appearance
Also, because bone is weaker and you put weight on it, there is a tendency to develop coxa vara, called a SHEPHERD’S CROOK DEFORMITY
◦
4.
No matrix
◦
Mainly just a lytic lesion
Seen in giant cell tumors: epi-metaphyseal, geographic, large and without matrix

Figure 12 Shepherd's crook deformity of upper femur.
6.
Laboratory exams
•
Choice of exams dependent on your working diagnosis
•
For infection: CBC ESR, CRP
•
For inflammatory arthritides: ESR, CRP, Uric Acid, rheumatic factor or RF (as needed)
•
Certain neoplasms: alkaline phosphatase (osteosarcoma)
◦
Alkaline phosphatase is a byproduct of osteoblasts
7.
Additional Imaging for Local Staging
1.
MRI
◦
◦
◦
◦
Useful for assessing soft tissue and intramedullay extent of the tumor
On T1, fat is bright. On T2, water is bright.
Should assess entire bone structure to determine intramedullary spread
This is needed for local staging before biopsy to get as much representative of the tumor
1.
CT Scan
•
More specific for bone lesions
•
Helpful for benign and aggressive tumors
8.
Types of Biopsies
1.
Closed Biopsy techniques
1.
Fine needle aspiration biopsy (usually gauge 23 needle)  cytology
•
Only one point of entry, then maneuver to direct yourself to different parts of the tumor
2.
Core needle biopsy (e.g. Tru-cut, Craig needle)  obtain a core of tissue, around 2 mm by 2 cm
2.
Open Biopsy Techniques

1.
Incisional
◦
Excising a piece of the tumor
◦
◦
2.
Excisional
◦
Remove whole bulk of the tumor
Done only if the tumor is small and without functional compromise
There is greater tumor access if you use core needle biopsy because different sites of the tumor are reachable, but incisional biopsy will give you more tissue. Pathologists usually prefer having more tissue.
9.
Some Principles in Biopsies for Musculoskeletal neoplasm
•
Done after history/PE, imaging and local staging
•
Performed by someone knowledgeable and skilled to do final procedure
(especially for incisional biopsy)
•
How:
•
Closed or open
•
Along lines of definitive surgery especially in limb salvage (because where your biopsy graft goes, you contaminate the graft; if you spread the tumor, you reduce the chance for limb salvage)
•
Away from major neurovascular structures
•
Very important to:
•
Use vertical incisions
•
Langer’s lines are followed for more cosmetic scars, but shouldn’t be considered in orthopedic tumors of the extremities! Langer’s lines cut perpendicularly, which can promote tumor contamination of other muscles and structures.
•
Close wounds near edge
•
Place drain near and along wound axis
◦
Some tumors bleed heavily so do more than just pressure packing: hematoma with cancer cells can develop, compromising possibility of limb salvage.
•
Superficial tumors are not necessarily benign!
•
20% of soft tissue malignancies are superficial.
•
Cartilage tumors often seed surrounding structures
10.
Incisional Biopsy Techniques
•
Do limited dissection
•
No flaps should be raised
•
Major neurovascular bundles should not be exposed
•
Dissection should be through a muscle and not between muscles because it will be less blood. If you do it in between muscles, you end up contaminating both
•
Incision is usually done through the iliac crest, below the iliac line. The gluteus is

◦
◦ used to cover the defect after the surgery.
•
Things to avoid
◦
Cutting through Langer’s lines
Interventional radiologists inserts needles blindly promoting spread
Excessively large incisions (2-3 cm is enough)
11.
Oncologic Surgical Margins
•
Aim is to cure disease and to preserve limb function.
•
These are achieved by using a combination of limb salvage surgery and adjuvant therapy.
•
Limb salvage operations are indicated if:
•
The tumor is situated in the extremities and/or the axial skeleton.
•
Tumor margins are amenable to surgery.
•
Only moderate soft-tissue extension is present.
•
Neurovascular bundles are intact.
•
Metastases are absent or amenable to curative treatment.
•
The patient is in good general health.
Type Plane of Dissection Microscopic
Appearance
Within lesion Tumor at margin Intracapsular/ intralesional
Marginal Within reactive zone extracapsular
Reactive tissue +/- microsatellites
Wide Beyond reactive zone through normal tissue
Normal tissue +/-
“skips”
Radical You take out the entire compartment
•
Conduct tumor staging before amputation to determine tumor extent. The
Enneking classification correlates the tumor stage with the excision margins as follows:
Stage 1 Latent
Surgical Margins for Benign Stages
Intracapsular excision (or curettage)
Stage 2 Active Extracapsular excision through the reactive zone
Stage 3 Aggressive Wide margins of resection or Marginal excision with adjuvant treatment (eg,

radiation therapy)
Stag e
Surgical Margins for Malignant Stages
Surgical Margin
IA Wide – usually excision; usually amenable to limb salvage
IB Wide – consider amputation vs. joint or neurovascular deficit; the choice between amputation and limb salvage depends on the estimated amount of residual tumor left behind after a limb salvage procedure
II Radical amputation or Disarticulation – Tumors are high grade, extra-compartmental, with significant risk for skip metastases. Those responsive to chemotherapy may be treated successfully using wide excision + adjuvant therapy.
III Aggressive resection and chemotherapy or Palliative resection – Tumors at this stage are responsive to chemotherapy. Those not responsive to adjuvant therapy are treated with palliative resection.
II.
BENIGN BONE NEOPLASMS
1.
Benign Fibrous Lesions
1.
Fibrous Cortical Defect, Non-ossifying Fibroma
•
Age: usually children and adolescents
•
Site: Metaphyseal cortical defect, long bones
•
Treatment: observation, can resolve on its own therefore just reassure the parents and the kid can do whatever he wants
•
Usually eccentric, metaphyseal, with marginal sclerosis.
•
Disappears by itself after growth plate closure, no intervention necessary.
•
Diagnosed by Xray.

Figure 13 (LEFT) AP view of the distal femur shows a solitary corticate lucent lesion within the posteromedial distal femoral cortex; this finding is consistent with a fibrous cortical defect. (RIGHT) AP view of the distal tibia shows a lobulated well-circumscribed nonossifying fibroma that is eccentrically located within the distal tibia metadiaphysis.
Peripheral sclerotic border with a central lucency is typical of this lesion.
2.
Fibrous dysplasia
•
Age: mono-ostotic – any age
•
Usually 5-20 years
•
Polyostotic – any age
•
Shepherd’s crook deformity aka coxa vara

•
Aberrant bone formation (colloquially, “goes haywire”)
•
Usually an incidental finding on x-ray
•
Recall: how is bone formed?
•
1st step – osteoid matrix with collagen, not calcified
•
2nd step – osteoid becomes woven bone when it becomes calcified
•
3rd step – at the woven bone matures, layering of collagen fibers occur. This is lamellar bone.
•
In fibrous dysplasia, it persists as woven bone with matrix that remains to be
fibrous tissue (few osteoblasts around woven bone). Therefore it appears as
ground glass on X-ray and causes varus deformity because of weak structure

Figure 14 Fibrous Dysplasia. Intramedullary diaphyseal lesion that blends w/ thinned, bulged cortex; Hazy or ground glass lesion which may occur w/ angular deformity; Angular deformity in bone is often present at the level of lesion; Active lesion may progress in size and deformity.

•
4 Forms:
1.
Monostotic – 70-80%
▪
▪
▪
▪
▪
▪
Initial symptom is pain of involved limb with a limp, a spontaneous fracture, or both.
3.
Craniofacial
▪
Pattern occurs in 10-25% in monostotic form, 50% with polystotic,
& isolated craniofacial
4.
Cherubism
Autosomal dominant, variable penetrance.
Occurs in children; more severe in boys.
Jaw is broad and protruding.
Symmetric involvement of maxilla&mandible
Regression may occur after adolescence.
•
Types of lesions:
•
CYSTIC type: radiolucent w/ a reactive rim, no trabeculae, & normal cortical thickness
•
PAGETOID type of lesion: trabecular pattern which is more dense than normal bone
•
SHEPHERD'S CROOK DEFORMITY: extensive involvement of proximal femur results in a characteristic varus deformity which resembles a Shepherd's crook
1.
Unicameral Bone Cyst
•
Age: Usually age 4-13, when children are not skeletally mature yet (almost exclusively in children)
•
Site: Metaphyseal but as the child grows older, it becomes Diaphyseal; doesn’t cross the growth plate and so it doesn’t enter the epiphysis
•
Falling leaf sign – a piece of the cortex falling down inside and lying down in there.
•
Natural history: eventually disappears after skeletal maturity
•
THERE IS NO KNOWN CAUSE.
•
Most have no symptoms or are discovered incidentally.
•
Medical Therapy: closed fracture care following pathologic fracture through the lesion
•
Surgical: Subtotal resection with and without grafting or Percutaneous treatment

techniques using steroid injections or mechanical disruption of cyst wall
Figure 15 Unicameral Bone Cyst
1.
Giant Cell Tumor
•
Age: Almost always skeletally mature patients, 20-30 yrs
•
Site: Epimetaphyseal
•
Many giant cells (multinucleated giant cells) - reaction to the stromal cells
•
AGGRESSIVE
•
Treatment: ranges from pure observation to amputation depending on the aggressiveness
•
Very bloody tumor: findings of hemosiderin pigments
Figure 16 Giant Cell Tumor of distal radius.
Note on bisphosphonates – medication binds to bone
•
When osteoClasts bind subsequently, their ruffled borders are affected by the medication, halting resorption

1.
1.
Benign Osseous Lesion
Osteoid Osteoma
•
Age: Usually ages 10-30 years
•
Site: Usually cortical. Classified as cortical, cancellous, or subperiosteal
•
Occurring in any bone.
•
But in about 2/3 of patients, the appendicular skeleton is involved. The skull and facial bones are involved exceptionally.
•
Composed of osteoid AND woven bone.
•
UNKNOWN ETIOLOGY.
•
Classic presentation: Focal bone pain at the site of the tumor.
•
Pain worsens at night and increases with activity, and is relieved with small doses of aspirin.
•
The lesion initially appears as a small sclerotic bone island within a circular lucent defect.
•
Central nidus seldom >1.5 cm in diameter, and it may be associated with considerable overlying cortical and endosteal bone sclerosis.
•
These tumors may regress spontaneously. The mechanism of this involution is not known, but tumor infarction is a possibility.
•
Produces prostaglandin E2 which causes pain. Can be relieved by NSAIDs or aspirin.
•
PGE2 also stimulates osteoblasts, therefore cortex thickens.
•
Nidus seen on imaging can be taken out with surgery or radiofrequency ablation.
•
Brown pigment seen inside: hemosiderin laden lesions
Figure 17 Osteoid osteoma with nidus. Nidus is an osteoid-rich tissue and interconnected bone trabeculae superimposed on a background of highly vascularized connective tissue containing large dilated vascular channels.
Nidus inside the cortex looks like a cherry red spot grossly.
High turnover bone due to prostaglandin E2 formation.
1.
Benign Cartilaginous Lesions
1.
Osteochondroma
•
A cartilage-covered bony excrescence (exostosis) arising from the surface of a bone.

•
The most common bone tumors in children!
•
Can affect any bone preformed in cartilage
•
Age: Average age is 10, and most occur before age 20 (< 1% becomes malignant)
•
Site: Surface lesion, metaphyseal
•
Solitary or multiple. May arise spontaneously or as a result of previous osseous trauma.
•
Aberration in growth plate: grows horizontal rather than vertical, stops growing when you stop growing
•
Complications of osteochondroma: fractures, bony deformities, neurologic and vascular injuries, bursa formation, and malignant transformation
•
If this grows continuously even after bones mature, it becomes an osteosarcoma.
But chance of becoming malignant is less than 1% per lesion.
•
No mode of inheritance
2.
Hereditary multiple exostoses, a.k.a. Multiple osteochondromatosis
•
Autosomal dominant – short stature, multiple osteochondromas, and asymmetrical growth at the knees and ankles  leading to deformities.
•
Close to the metaphyses, and they may be sessile or pedunculated.
•
Cortex of the lesion is continuous with the cortex of the bone, with a homogeneous continuation of the medulla.
•
The leg-length inequality is usually about 4 cm, and the risk of malignant degeneration is between 1% and 20%.
Figure 18 Multiple osteochondromatosis. Fractures of the lower tibia and fibula as a complication of hereditary multiple exostoses. Note the osteochondromas involving the calcaneum and the upper and lower portions of the tibia and fibula.
3.
Enchondroma
•
Ectopic hyaline cartilage rests (likely displaced from the growth plate) in

intramedullary bone.
•
Lesions replace normal bone with mineralized or unmineralized hyaline cartilage, thereby generating a lytic pattern on radiographs or, more commonly, a lytic area containing rings and arcs of chondroid calcifications.
•
Age: Almost any age, but usually 15-40
•
Site: inside shaft
•
Usually solitary lesions in intramedullary bone.
•
Primary significant factors: pathologic fracture and a small incidence of malignant transformation
•
When multiple enchondromas coexist, the diagnosis of enchondromatosis should be considered.
Figure 19 Enchondroma. Frontal radiograph of the left hand demonstrates an expansile lytic lesion in the proximal phalanx of the middle finger with a distinct zone of transition, thinning of the cortex, and a pathologic fracture.
III.
MALIGNANT BONE NEOPLASMS
1.
Metastatic Carcinoma
•
Site: Axial skeleton, proximally appendicular skeleton
•
Most common carcinomas that metastasize to bone:
(1) breast
(2) lung
(3) kidney
(4) prostate
(5) thyroid
•
These account for around 85% of skeletal metastasis
•
Females – Breasts and lungs are the most common primary disease sites (80%)
•
Males – Prostate and lungs (80%)
•
Kidney, gut, and thyroid, as well as sites of unknown origin – account for the remaining 20% in both sexes

•
Sometimes there are bone metastasis but without lung metastasis, even if the lungs could act as a filter for the blood for metastasis
▪
Batson’s plexus of veins
•
Reason for cancer spread without going through the usual/normal blood circulation
•
Veins that have communication to these organs (enumerated above), to the axial skeleton, and the proximal appendicular skeleton (humerus and femur).
•
Valveless.
•
Has no valves so blood can go both ways; possible backflow if increased
▪ abdominal pressure; reason why some tumors can spread to bone without going through lungs
Acral metastasis
•
Unusual sites of metastasis (ex. at distal phalanx) because of lung metastasis – circulation brings it anywhere.
2.
Multiple Myeloma
•
MOST COMMON PRIMARY BONE TUMOR
•
Disease characterized by proliferation of malignant plasma cells and a subsequent overabundance of monoclonal paraprotein. The antibody-forming cells (ie, plasma cells) are malignant and, therefore, may cause unusual manifestations.
•
Age: increasing frequency with age, usually > 50
•
Myeloma site: solitary to multiple
•
Histology: plasma cells which usually mature in the blood stream and produce immunoglobulins
•
Usual “punch-out lesions”
•
Bone scan: usually cold
•
Medical:
▪
▪
▪
▪
▪
Bisphosphonates for prophylaxis
Erythropoietin for anemia
Corticosteroid therapy to reduce spinal swelling
Plasmapharesis with ARF
Hydration to maintain a urine output of >3 L/d)
▪
▪
Management of hypercalcemia
Avoidance of nephrotoxins
•
Treatment: Autologous bone marrow transplantation or radiation

Figure 20 Multiple myeloma bone biopsy showing sheets of malignant plasma cells.
Figure 21 Mulitple myeloma bone marrow aspirate Note the blue cytoplasm, eccentric nucleus, and perinuclear pale zone (or halo)
3.
Ewing’s Sarcoma
•
Age: usually children and young adults, 4-15 years and rarely develops in adults older than 30 years
•
Round cell tumor
•
Site: diaphyseal (long bones), pelvis
•
Histology: round cells
•
Onion skin/peeling appearance
•
Highly malignant primary bone tumor derived from red bone marrow

•
THE 2ND MOST COMMON MALIGNANT BONE TUMOR IN YOUNG PATIENTS, AND
IT IS THE MOST LETHAL BONE TUMOR
•
Associated with primitive peripheral neuroectodermal tumor (PNET)
•
Most frequently, tumor is diagnosed as a monostotic lesion in the metaphysis or diaphysis of the long bones of the extremities. The tumor may also occur, although less frequently, in the pelvic area, ribs, and scapulae. In fact, any bone may be involved.
4.
Osteogenic Sarcoma
•
Age: usually ages 10-25
•
Site: Ends of long bones, usually around knee, proximal humerus, epi-metaphyseal and can go to diaphyseal area
•
Histology: what makes it malignant is not the bone itself but the cells around it
•
Lace-like pattern, sunburst appearance
•
Osteoid formation on x-ray
•
Malignant because of malignant osteoblasts
5.
Chondrosarcoma
•
Age: usually age 30 to 60 years
•
Site: metaphyseal diaphyseal
•
2nd most frequent group of primary malignant tumor of bone (25% of all primary osseous neoplasms), with highly diverse features and behavior patterns
(slow-growing non-metastasizing lesions to highly aggressive metastasizing sarcomas)
•
Firm, well demarcated, lobulated lesion, not more than 3cm in maximum diameter.
•
Chondroid matrix
•
Consists of mature hyaline cartilage. Focal fibrosis, ossification or myxoid changes may be noted in some cases. Richly vascular interlobular connective tissue is often noted.
•
On MRI – dark on T1 (new mnemonic: “T2 tubig”)
•
The sheet can be excised without affecting the nerve
Figure 22 Chondrosarcoma, frontal radiograph of the pelvis demonstrates extensive

calcification overlying the left ilium and in the lateral soft tissues. No bone destruction is shown. High-grade secondary peripheral tumor.
Figure 23 Chondrosarcoma, MRI. T1-weighted axial MRI of the pelvis demonstrates the low signal intensity of the acetabular lesion. Low-grade central tumor.
IV.
BENIGN SOFT TISSUE TUMORS
1.
Lipoma
•
Age: usually adults
•
The body can’t metabolize the fat of lipoma
•
Benign subcutaneous nodule, mass, or tumor composed of mature fat cells usually occurring on the trunk, neck, back, upper thighs, and arms.
•
Affect both sexes, and all ages.
•
Symptoms: Painless slow growing swelling beneath the skin.
•
Treatment: Observation, surgery if it starts to grow quickly or for cosmetic reasons.
•
Body cannot metabolize fat in lipomas even during starvation

2.
Hemangioma
•
Abnormal proliferation of blood vessels that may occur in any vascularized tissue
•
Age: young adults
•
Skeletal muscle is the most common site for hemangioma of the deep soft tissue.
•
Symptoms: Intramuscular hemangiomas  pain and swelling. Bone hemangiomas
 may be symptomatic or an incidental finding.
•
Commonly localized to a single area, but multiple hemangiomas may occur in a single individual in a process known as hemangiomatosis
•
X-ray – phleboriths – calcification in the blood vessels
•
NOT A NEOPLASM: an aberrance in the growth of tissues.
3.
Neurilemomma
•
Tumor is from the nerve sheath
•
Can be taken out completely without cutting the nerve
•
Benign, encapsulated tumors of the nerve sheath, though to originate from
Schwann cells derived from the neural crest.
•
Usually arise from the side of a nerve, are well encapsulated, and have a unique histologic pattern.
•
Age: usually adults
•
Histology: verrucae body – palisading nuclei
•
Presentation: Vary because they can present in many locations. If it involves the

spinal nerve roots  mimic herniated disk disease of the spine. In the extremities  present either as an asymptomatic mass or as mild, localized pain and paresthesia resulting from pressure on the nerve of origin.
•
Masses are slow growing and can exist for months to years without producing symptoms. The average time from onset of symptoms to diagnosis is 5.5 years.
Figure 25 Neurilemmoma. (LEFT) The cell of origin for a neurilemmoma is the Schwann cell, which is derived from the neural crest. These cells line the peripheral nerve processes.
(RIGHT) Neurilemmomas have very distinctive appearances on magnetic resonance images. Many investigators believe that the presence of a target sign on a peripheral nerve is diagnostic for a neurilemmoma
4.
Neurofibroma
•
Age: usually age 20’s
•
Arises from nerve fiber. You cannot take the tumor out without cutting the nerve.
•
Multiple painless lumps
•
Nerve nuclei has wavy kinky pattern
•
In neurofibromatosis, there is no way to remove the lesion but cutting off the nerve

Figure 26 Neurofibroma. There is poor fat suppression of the right thigh so the normal marrow appears brighter than on the left. Inhomogeneous fat suppression creates

difficulty distinguishing gadolinium enhancement from fat, particularly within the marrow
(LOWER RIGHT) Higher-power view of a neurofibroma reveals spindled cells with wavy nuclei embedded in an acidophilic stroma. Mast cells are increased in number.
V.
MALIGNANT SOFT TISSUE TUMORS
1.
Liposarcoma
•
Slowly enlarging, painless, non-ulcerated submucosal mass in a middle-aged person, but some lesions grow rapidly and become ulcerated early
•
The most common soft tissues tumor accounting for approximately 20% of all sarcomas in adults
•
Age: Adults; occurs predominantly in patients >50 yo, very rare in childhood.
•
Typically appear in the deepest tissues of limbs proximal portions, predominantly in the thigh (30% a 40% of cases).
•
World Health Organization classification:
•
Well-differentiated, which includes the adipocytic, sclerosing, and inflammatory subtypes
•
De-differentiated
•
Myxoid
•
Round cell
•
Pleomorphic
•
3 Biologic Forms:
1.
Well-differentiated liposarcoma
2.
Myxoid and/or round cell
3.
Pleomorphic
•
Many types can exist in one lesion, so look for heterogeneity through MRI especially for deep-set soft tissue tumors (lipoma may be liposarcoma)

Figure 27 Well-differentiated liposarcoma; When viewed under the microscope, they look like fat cells. In between fat cells are lipoblasts that are not benign.
Figure 28 Pleomorphic liposarcoma. The rarest one, accounting for about 5% of all liposarcomas.

2.
Malignant Fibrous Histiocytoma
•
Tumor rich in histiocytes with storiform growth pattern
•
Age: usually occurs in adults, peaking in the 70’s
•
Histology: Storiform (pleomorphic), Myxoid, Giant cell, Inflammatory subtype
•
Storiform is most common (70%), followed by myxoid variant (20%). The last two subtypes are rare.
•
Treatment: Complete surgical excision complemented by adjuvant radiotherapy
Figure 29 MFH. Classic storiform-pleomorphic malignant fibrous histiocytoma pattern showing short fascicles of spindle cells radiating from a central point, intermixed with neoplastic giant cells in the pleomorphic portion.

Figure 30 Myxoid type MFH. In order for a tumor to be characterized as a myxoid variant, myxoid tissue must account for at least half of the tumor. This variant is less aggressive with a better prognosis.
3.
Fibrosarcoma
•
Malignant neoplasm (cancer) of mesenchymal cell origin in which histologically the predominant cells are fibroblasts that divide excessively without cellular control; they can invade local tissues and travel to distant body sites
(metastasize).
•
Age: Adult – usually 30s to 50’s
•
Infantile – usually first year of life
•
Histology: Herring bone
•
Fibrosarcoma has a broader age distribution and is even less common than osteosarcoma.
•
Radiographically, bone lesions of fibrosarcoma are generally osteolytic (bone destroying)

Figure 31 Fibrosarcoma. Herringbone pattern, or fasciculated, pattern of spindle cells and an indistinct cell borders. The absence of giant cells is an important feature in distinguishing fibrosarcoma from malignant fibrous histiocytoma.
4.
Embryonal Rhabdomyosarcoma
•
Malignant mesenchymal tumor of prostate with morphologic and molecular differentiation toward skeletal muscle.
•
MOST COMMON MALIGNANT PROSTATIC TUMOR IN INFANCY AND CHILDHOOD
•
Firm, smooth enlargement. Usually extraprostatic extension
•
Age: usually children
•
Many variants – round cell, alveolar, pleomorphic
•
Therapy: Highly effective with multidrug chemotherapy combined with limited surgery and radiation. Pelvic exenteration for unresponsive cases
•
Responsive to chemotherapy

Figure 32 Embryonal rhabdomyosarcoma. Sagittal T1-weighted magnetic resonance (MR) image shows a well-circumscribed extraconal mass (arrowhead) superior to the ocular globe and isointense relative to muscle

Figure 33 Embryonal Rhabdomyosarcoma. As evidenced by a variable cell population consisting of small, round tumor cells with hyperchromatic nuclei and of large, polygonalshaped tumor cells with abundant eosinophilic cytoplasm, which often contains diagnostic cross striations (arrow).
Sarcomas:
Good prognosis Bad prognosis
Size
Site
Small < 5 cm
Superficial
Big > 5 cm
Deep
Histologic grade Low High
•
Smaller lesions have better prognosis
VI.
SAMPLE CASES
1.
Large lesions, epi-metaphyseal, geographic border, eccentric, no cortical break, no soft-tissue component, (no matrix) lytic, epiphysis closed (adult), non-aggressive, benign
•
Diagnosis: giant cell tumor, aneurismal bone cyst
2.
Large, epi-meta-diaphyseal of distal femur, permeative border, sunburst

periosteal reaction, Codman’s triangle, osteoid matrix, cortical break with soft tissue component
•
Diagnosis: Osteosarcoma
3.
Large, meta-diaphyseal, surface of the distal femur, multiple lesions in proximal tibia and fibula, bilateral; opened growth plate; multiple surface lesions, sessile or pedunculated
•
Diagnosis: Multiple osteochondromatosis (mode of inheritance: autosomal dominant)
4.
Large lesion, involving the proximal metaphyseal area of the femur, geographic border, no cortical break with, no soft tissue component, lytic, young patient, growth plate open, no matrix
•
Diagnosis: Unicameral bone cyst
END
Team 9 | Abelanes, Asperas, Bionat, Cansana, Chung, del Prado, Hao, Rivera, Tud
Page 18 of 18