What is the recommended surveillance for enchondromas (cartilage tumors)?

Surveillance for Enchondromas

For solitary, asymptomatic enchondromas without concerning radiographic features, regular radiographic follow-up is sufficient and more appropriate than routine surgical intervention, given the rare risk of malignant transformation and considerable complication rates associated with curettage. 1

Solitary Enchondromas

Initial Assessment and Baseline Imaging

• Obtain baseline plain radiographs at the time of diagnosis to document the lesion's size, location, and characteristics 2
• Consider baseline MRI for lesions with any concerning features (pain, size >3 cm, cortical erosion, or aggressive appearance) to better characterize the lesion and guide management 3

Surveillance Protocol for Stable Lesions

The recommended surveillance strategy for asymptomatic, stable-appearing enchondromas is:

• Plain radiographs every 3-6 months for the first year 2
• Annual plain radiographs for at least 3 years of total follow-up 2
• After 3 years of documented stability, consider discontinuing routine surveillance in truly asymptomatic patients 2

When to Escalate Imaging

Obtain dedicated MRI imaging if any of the following develop:

• New or increasing pain attributable to the lesion 4
• Radiographic evidence of growth or increasing size 4, 2
• Development of cortical erosion/scalloping >2/3 of cortical thickness 3
• Cortical penetration or expansion of bone 3
• Soft tissue extension 5

Cost-Effectiveness Considerations

• Avoid routine MRI surveillance in the absence of clinical or radiographic concern, as this represents the most significant opportunity for cost savings without compromising oncologic safety 2
• The median annual costs for plain radiographs ($609) versus MRI ($2,241) demonstrate substantial financial burden with routine advanced imaging 2

Multiple Enchondromas (Ollier Disease and Maffucci Syndrome)

Enhanced Surveillance Due to Higher Malignancy Risk

Patients with enchondromatosis require more intensive surveillance given the 30% risk of malignant transformation to chondrosarcoma: 4

Comprehensive Surveillance Protocol

Physical Examination:

• Every 6-12 months starting from birth/diagnosis 4
• Assess for pain, increasing tumor size, and functional limitations 4
• In Maffucci syndrome, include neurologic examination for gliomas and assessment for lower abdominal pain in women (juvenile granulosa cell tumors) 4

Whole-Body MRI (WBMRI):

• Baseline WBMRI at diagnosis (defer if general anesthesia would be required in young children) 4
• In childhood: baseline imaging only 4
• After age 20 years: periodic WBMRI given the median age of transformation (30-52 years, but can occur as young as 10 years) 4
• Add dedicated brain MRI with WBMRI after age 20 or if neurologic symptoms develop 4

Plain Radiographs of Known Lesions:

• Every 2-3 years from the time of identification 4

High-Risk Lesion Surveillance:

• Annual dedicated MRI for lesions >5-6 cm or located in the pelvis/scapula (sites with highest transformation rates including femur, tibia, humerus, pelvis, scapula) 4

Red Flags Requiring Immediate Evaluation

Any of the following warrant targeted MRI and consideration of biopsy:

• Pain or increasing pain at lesion site (though note that pain is not uniformly present, and some chondrosarcomas are asymptomatic) 4
• Increasing tumor size on serial imaging 4
• Cartilage cap thickness >2.0-3.0 cm on MRI or CT 4, 6
• Rapid growth of lesion 4

Key Clinical Pitfalls

Diagnostic Challenges

• Differentiation between enchondroma and grade I chondrosarcoma is notoriously difficult even for expert pathologists, with significant interobserver variability 4
• In phalanges of hands and feet, malignancy is extremely rare; however, in other long bones, central cartilaginous lesions should be considered low-grade chondrosarcoma until proven otherwise 4
• Pain at a cartilaginous lesion site may indicate malignancy but is not diagnostic—some chondrosarcomas are asymptomatic while some benign enchondromas cause pain 4

Avoiding Overtreatment

• The complication rate of enchondroma curettage is considerable (23% in one series), supporting conservative management for stable lesions 1
• Malignant transformation of solitary enchondromas is rare (5.45% growth rate in one series, with only 1 of 7 biopsied lesions showing grade 1 chondrosarcoma) 2
• Most enchondromas are discovered incidentally and are frequently associated with adjacent joint pathology that is the actual source of symptoms 5

Multidisciplinary Management

• Orthopedic oncology providers should be involved in monitoring, particularly for enchondromatosis patients 4
• Consider referral to academic centers with expertise in rare bone tumor syndromes for patients with Ollier disease or Maffucci syndrome 4