Bone Surface Lesion

DIFFERENTIAL DIAGNOSIS

Common

• Osteochondroma
• Other Benign Bone Tumor
• Malignant Bone Tumor

Less Common

• Metastases
• Bone Tumor Recurrence
• Acute Osteomyelitis
• Chronic Osteomyelitis
• Fracture
• Orthopedic Implant
• Cortical Tug Lesion
• Juxtacortical Tumor

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

• Radiographs or other imaging very helpful when assessing bone surface lesions on US
• US cannot assess intramedullary extent or surrounding bone quality
• Beware of normal bone irregularity at sites of muscle insertion and previous surgery
• Heavy calcification or ossification alongside bone may appear attached to bone on US
• Only portion of bony lesion visible with US

Angulation of transducer can help provide more comprehensive evaluation

MR or CT is often required for complete evaluation
• Determining etiology of surface bone lesions is often helped by clinical features

Age of patient

Location of lesion

Duration and type of symptoms
• US-guided biopsy of bone tumor is possible if extraosseous mass is present
• US-guided biopsy of intramedullary component of bone tumor or infection is possible via cortical breach if present

Helpful Clues for Common Diagnoses

• Osteochondroma

Most common bone surface tumor

Metaphyseal or metadiaphyseal in location

– Points away from joint

Majority are solitary

– If multiple and metaphyseal dysplasia indicates multiple hereditary exostoses (diaphyseal aclasis)

Variable thickness in hypoechoic cartilage cap

– Often not visible or barely visible

– Cap thickness of ≥ 2 cm or progressive thickening of cartilage cap on serial imaging is strongly indicative of secondary chondrosarcoma

Most osteochondromas are asymptomatic

Symptoms can be due to several causes

Reactive myositis secondary to friction between osteochondroma and adjacent muscle

– Degree of myositis is best evaluated on MR

Reactive bursitis

– Friction between osteochondroma and soft tissue can lead to development of intervening adventitial bursa

Pseudoaneurysm

– Most common vascular complication

– Arterial rupture → arterial lumen contained by hematoma

– Characteristic to-and-fro pattern on spectral analysis of narrow neck

– Characteristic yin-yang bidirectional flow pattern on color Doppler imaging of lumen

Bleeding

– From vascular injury, hemorrhagic bursitis, or myositis

Neurological sequelae

– May cause compressive neuropathy, radiculopathy, or myelopathy depending on location

– Snapping nerve → reactive neuritis

Fracture

– Affects stalk of pedunculated osteochondroma

Malignant transformation more common with

– Diaphyseal aclasis (likelihood ~ 1%)

– Increase in age

– Osteochondromas located in axial skeleton
• Other Benign Bone Tumor

Most intramedullary benign tumors remain intramedullary

– May expand bone cortex or fracture → bone surface irregularity

Giant cell tumor of bone, not infrequently, has extraosseous soft tissue component

– Hypervascular ± hemorrhagic cystic areas

Other benign juxtacortical tumors

– Chondroma, fibroma, schwannoma
• Malignant Bone Tumor

Osteosarcoma is most common malignant bone tumor

– Usually occurs in childhood or young adulthood

Most frequently arises at long bone metaphysis

– Area of most rapid growth in childhood

Hypoechoic, broad-based tumoral outgrowth from bone

Radiating seams of tumoral osteoid deposition

Moderately hyperemic

Helpful Clues for Less Common Diagnoses

• Metastases

Can be detected by US if surface based or cortex disrupted

Lung and breast are most common primary sites

– Adenocarcinoma is most common tumor cell type

Predilection for diaphyseal location

– Compromises bone strength as cortical bone is particularly relevant for diaphyseal bone strength
• Bone T umor Recurrence

US is very useful at screening for bone tumor recurrence

Based on premise that most bone tumor recurrences occur in juxtacortical soft tissues rather than in bone

Unlike MR, US assessment of juxtacortical soft tissues is not affected by metallic prosthesis

Tumor recurrence usually mirrors imaging characteristics of original tumor

If recurrence is detected, check regional lymph nodes, as nodal involvement is more frequent with recurrence than with primary bone tumor

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Apr 9, 2020 | Posted by admin in MUSCULOSKELETAL IMAGING | Comments Off

DIFFERENTIAL DIAGNOSIS

Common

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

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Radiology Key

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Bone Surface Lesion

Bone Surface Lesion

Less Common

Helpful Clues for Common Diagnoses

Helpful Clues for Less Common Diagnoses

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Fastest Radiology Insight Engine

Bone Surface Lesion

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