Bone Tumor Mimickers

Jim Wu, MD

Beth Israel Deaconess Medical Center Harvard Medical School

Boston, MA

Disclosures

– Kaneka Corp - research funding support

– Boehringer Ingelheim - research funding support

– PharmaMar - imaging consultant

Learning Objectives

• Learn the definition of a bone tumor mimicker

• Learn the categories of bone tumor mimickers

• Learn the key imaging and clinical features of bone tumor mimickers in order to prevent inappropriate treatment

Bone Tumor Mimicker

• Definition of “Mimicker”

– to be an imitation of, simulate; resemble closely

• “Bone tumor mimicker” - any lesion in bone that looks like a bone tumor

-Merriam-Webster Dictionary

Case 1

Case 2

T1 T2 fat sat

Case 3

Case 4

Bone Tumor Mimicker

• Many lesions in bone can be mistaken for a tumor

• Important to know the common mimickers in order to prevent misdiagnosis and inappropriate treatment

• Do not want to subject patient to unnecessary tests and anxiety

Classification of Bone Tumor Mimickers

• Normal variants

• Congenital/developmental

• Trauma

• Metabolic/Arthritic

• Infection

• Iatrogenic

• Technical artifacts

Normal variants

•Red marrow

•Ward’s triangle in femur

•Humeral pseudocyst

•Calcaneal pseudotumor

T1 T2 fat sat

Lesion hyperintense to muscle on T1

Abnormal Marrow - Lymphoma

T1 T2 FS

Key Point: Red marrow should not be hypointense to normal skeletal muscle on T1

Red Marrow

• Normal marrow transitions from red to yellow (fatty) marrow with increasing age

• Islands of red marrow can remain, especially in the metaphysis of long bones

• Red marrow should be more hyperintense than skeletal muscle on T1 weighted images

• Red marrow should not extend into the epiphysis, stopping at the physeal scar

Red Marrow

Ends at physeal scar

B Cell Lymphoma

T1 T2 FS

Ward’s triangle

• Triangular area of lucency in femoral neck

• Outlined by the compressive and tensile trabecular lines

• Less apparent in osteoporotic patients due to loss of trabecular lines

• NORMAL FINDING!

Humeral pseudocyst

• Lucent area in the superolateral aspect of the humeral head

• Due to normal decrease in trabecular lines and often contains more fat than the rest of the humeral head

• Best seen on external rotation views

Normal fat

Pseudocyst in the anterior calcaneus

• Lucency in the body/anterior aspect of the calcaneus can appear in an area between major trabecular groups

Intraosseous Lipoma

Congenital/ developmental

•Synovial herniation pit in proximal femur (Pitt’s pit)

•Supracondylar process of humerus

•Soleal line on tibia

Synovial herniation pit in proximal femur (Pitt’s pit)

• Dr. Michael Pitt in 1982• Anterosuperior aspect of the

femoral neck• Rounded lucent lesion with a

thin sclerotic rim• ?? normal variants or due to

mechanical abrasion of hip capsule with femoral neck

• Associated with femoral acetabular impingement (FAI) syndrome

Supracondylar process of the humerus

-Bony spur arising from the anteromedial aspect of the humerus

-1-3% of population

-Phylogenetic vestige of the supracondyloid foramen

-Incidental finding and should not be mistaken for an osteochondroma or surface osteosarcoma

-Ligament of Struthers can form fibrous tunnel which compresses median nerve and/or brachial artery

Supracondylar process of the humerus

http://www.abdn.ac.uk/zoohons/struthers/ligament1.htihttp://www.abdn.ac.uk/zoohons/struthers/ligament1.hti

Soleal line

Soleal line

• A tug lesion at the origin of the soleus muscle

• Can mimic periostitis from trauma, tumor or infection

• The cortical thickening extends lateral to medial down the posterior upper one-thirds of the tibia

• Similar changes can be seen at the fibular attachment of the soleus

Soleal line

Stress Fracture Osteoid OsteomaSoleal Line

Trauma

• Subperiosteal hematoma

• Stress fracture

• Myositis ossificans

T1

Subperiosteal hematoma

• Surface bone lesion caused by bleeding in the periosteum

• Periosteum is highly vascular and closely adherent to the bone

• Often resolve with no sequela; however, lesions that persist can ossify

Stress Fracture

• Overuse injuries caused by repeated stress to bone

• (1) insufficiency fractures occur when normal stress is applied to pathologically weakened bone

• (2) fatigue fractures occur where excessive repetitive force is applied to normal bone

Stress Fracture

Resolved6 months later

Myositis Ossificans

Myositis Ossificans

• Most common form of heterotopic ossification in muscle • Predisposing factors: burns, paraplegia, surgery, traumatic

brain injury, hemophilia, ankylosing spondylitis, DISH• Patients often cannot recall previous trauma • Most lesions arise in the large muscles of the extremities• Calcification is rarely seen on radiographs in the first few

weeks• Peripheral “zonal” ossification pattern• Early-stage myositis ossificans can enhance and can be

mistaken for a soft tissue sarcoma as the characteristic zonal ossification pattern is not present

Metabolic/arthritic processes

• Brown tumor of hyperparathyroidism

• Melorheostosis

• Osteonecrosis

• Paget’s disease

• Calcific tendinitis (resorptive phase)

• Subchondral cyst (geode)

6 months after removal of parathyroidadenoma

 Brown Tumors in

Hyperparathyroidism

 Brown Tumors in

Hyperparathyroidism

• Develop in untreated hyperparathyroidism (10 or 20) • Brownish blood products give rise to its name• 5% of patients with hyperparathyroidism • Well-defined lytic lesions with or without septations and

can expand the bone appearing aggressive• With treatment, e.g. removal of the parathyroid adenoma,

the lesions can become sclerotic• The lack of a change in the appearance of the lesion with

treatment should raise suspicion for an alternative diagnosis

Melorheostosis

• Benign bone dysplasia characterized by sclerotic bone lesions

• Involves bones in sclerotomal distribution

• “dripping candle wax” appearance

• 50% will show signs of the disease by age 20

• Pain, limb deformities related to muscle and tendon shortening, skin disorders, and poor circulation. But mostly asymptomatic

• Can be mistaken for a surface osteosarcoma or osteochondroma

OsteochondromaParosteal Osteosarcoma

Osteonecrosis

• Ischemic necrosis of the bone and marrow

• Causes: trauma, steroids, hemoglobinopathies, alcoholism, pancreatitis, SLE, Gaucher’s, irradiation, Caisson disease

• (1) bone infarcts occur in metaphysis and diaphysis

(2) AVN involves the subchondral bone and that can lead to collapse of the articular surface

• Serpentine double line T2 signal on MRI

Paget’s Disease

Lytic phaseChronic phase

Paget’s Disease • Chronic abnormal bone remodeling leading to osseous expansion

and deformity

• Rare <55 and Chinese 

• Linked to paramyxoviruses

• Complications: pain, fractures, hearing loss, increasing head size, renal stones, loose teeth, and high output cardiac failure

<1% malignant transformation to a sarcoma

• Active phase characterized by bone resorption.

– Extends from end of long bone to mid-diaphysis in a “blade of grass” or “flame” pattern

– Tibia is exception, lucent area may be centered in the diaphysis

• Pelvis is the most commonly involved site and often unilateral

Calcific Tendinitis

• Hydroxyapatite deposition disease (HADD)

• Deposition of calcium hydroxyapatite crystals in the tendons

• Most common in the tendons of the rotator cuff and the hip, however, it can involve any tendon

• Acute flare show ill-defined faint calcifications at tendon attachments.

Breast CA MetastasisCalcific Tendinitis

Osteoarthritis

T1

T2 FS

Subchondral Cyst

• Very common• Due to osteoarthritis• Synovium and joint fluid

enters bone via defect in the articular cartilage due to increased joint pressure

• Abut the joint surface, and have a sclerotic margin

Infection

• Brodie’s abscess

Brodie’s abscess (infection)

Osteoid Osteoma

Brodie’s Abscess• Imaging appearance depends on clinical stage

• Acute stage

– Radiographs reveal periostitis, cortical destruction, endosteal scalloping. Soft tissue swelling, abscess, and gas formation

• Subacute or chronic osteomyelitis

– Brodie’s abscess, often in metaphysis of long bones.

– Lucent lesion with surrounding sclerosis

– Sinus tract extending away from the center can help to distinguish a Brodie’s abscess from other lesions (i.e. osteoid osteoma)

Brodie’s abscess

Iatrogenic causes

• Biceps tenodesis

• Bone marrow biopsy

• Particle disease

• Radiation changes

Biceps tenodesis

• The long head of the biceps tendon is cut and reattached to the proximal humeral diaphysis

• Performed for treatment of biceps tendinitis and tear

Bone marrow biopsy

• Bone marrow aspirate commonly attained from the iliac bone from a posterior approach

• Edema in the marrow following bone marrow biopsy should not be mistaken for a focal lesion

Particle disease

• Most common cause of hardware failure

• Polymethylmethacrylate cement, polyethylene, or metal incites a macrophage-mediated granulomatous response stimulating osteoclast activity

• Lucencies surrounding the hardware components

• Unlike mechanical loosening, lytic areas do not follow the outline of the prosthesis

Radiation changes

• In early stage (hours to days), radiation causes vascular congestion, edema, and hypocellularity in the bone marrow. Low signal on T1 and high on T2

• Later (weeks to months) the bone marrow will be replaced with fat and occasionally fibrosis

• Often see line of demarcation from abnormal tissue with normal tissue outside of the irradiated field T1

Radiation changes

Technical artifacts

• Humeral head (internal rotation view)

• Radial tuberosity (lateral view)

• MRI pulsation artifact

• MRI wrap-around (aliasing) artifact

• External objects

These lesions are not real!

External RotationInternal RotationLesion disappears

Humeral head pseudolesion on internal rotation view

• Appears in humeral head on the internal rotation view

• Sharp sclerotic border forms at humeral head/neck junction as the diameter of the bone changes abruptly

• Lesion disappears on the external rotation view

Radial tuberosity pseudolesion on lateral view

Lateral view AP viewLesion disappears

Pulsation Artifact

MRI pulsation artifact

• Ghosting artifact from pulsatile arterial or venous flow can mimic lesions as image data from the vessels are superimposed onto bone or soft tissue

• Exchanging the phase and frequency encoding directions can help to resolve whether or not the lesions are real

MRI wrap-around (aliasing) artifact

Lipoma Sebaceous cyst on the back projecting over arm from wrap-around artifact

External object artifact

Normal fatNo lesion

External object artifact

• Objects lying over or under the patient can mimic a bone lesion

• Especially problematic in acute trauma where studies need to be performed quickly and imaging technique may not be optimal

Bone Tumor Mimickers– Normal variants

• Red marrow• Ward’s triangle in femur• Humeral pseudocyst• Calcaneal pseudotumor (anterior

aspect)

– Congenital anomalies/ developmental

• Synovial herniation pit in proximal femur (Pitt’s pit)

• Supracondylar process• Soleal line on tibia

– Trauma • Subperiosteal hematoma• Stress fracture• Myositis ossificans

– Metabolic/arthritic processes• Brown tumor of

hyperparathyroidism• Melorheostosis• Osteonecrosis• Paget’s disease• Calcific tendinitis (resorptive

phase)• Subchondral cyst (geode)

– Infection• Brodie’s abscess

– Iatrogenic• Biceps tenodesis• Bone marrow biopsy• Particle disease• Radiation changes

– Technical artifacts• Humeral head (internal rotation

view)• Radial tuberosity (lateral view)• MRI pulsation artifact• MRI wrap-around (aliasing) artifact • External objects

Melorheostosis-Cortical thickening-multiple bones in sclerotomal distribution

Case 1

Paget’s Disease

-Cortical and medullary sclerosis and enlargement-Increase activity on bone scan

Case 2

Red Marrow

-T1 signal is hyperintense to muscle

Case 3

Case 4

Brown tumors – hyperparathyroidism

“salt and pepper” skull from bone resorption

Case 4

bony resorption of the middle phalanges

Summary/Pearls• Many lesions can be mistaken for a bone

tumor

• Bone tumor mimickers can be due to many disorders and imaging artifacts

• High index of suspicion and knowledge of the common bone tumor mimickers will prevent misdiagnosis and inappropriate treatment

Suggested Reading

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