Enchondroma is a benign cartilage tumor located within the medullary cavity and is classified as the second most common benign bone tumor. Small tubular bones of the hands and feet (phalanges, metacarpals) are the most commonly affected sites, and the metaphysis of long bones is also a frequent location. It is usually detected incidentally and is asymptomatic. Radiologically, it appears as a well-defined, intramedullary lesion containing chondroid matrix calcification (arcs and rings). Its distinction from low-grade chondrosarcoma is one of the most important differential diagnostic challenges in radiology.
Age Range
20-50
Peak Age
35
Gender
Equal
Prevalence
Common
Enchondroma forms through aberrant direction of cartilage cell islands from the growth plate (physis) into the medullary cavity, where they remain as cartilage without ossifying (endochondral ossification defect); these heterotopic cartilage islands grow within the medullary cavity forming mature hyaline cartilage lobules. Endochondral ossification continues at the periphery of the lobular cartilage structure producing calcification — this peripheral calcification manifests radiologically as arcs and rings mineralization pattern and is the most characteristic imaging finding of chondroid matrix. Due to the benign nature of enchondroma, it does not produce cortical destruction (endosteal scalloping) or it is minimal — endosteal scalloping <2/3 of cortical thickness supports benignity, >2/3 raises suspicion for chondrosarcoma. On MRI T2-weighted sequences, markedly high signal is seen due to the 70-80% water content of hyaline cartilage; this T2 signal characteristic is common to all cartilage tumors, but the absence or minimal enhancement of enchondroma is the most important MRI finding distinguishing it from chondrosarcoma.
Well-defined lesion containing arcs and rings chondroid matrix calcification in the medullary cavity without significant endosteal scalloping (<2/3 cortical thickness), non-enhancing — in an asymptomatic patient with stable size, this combination is the most characteristic radiological appearance of benign enchondroma.
Characteristic arcs and rings chondroid matrix calcification within a well-defined lesion in the medullary cavity. Calcification density is variable — dense in some lesions, sparse or absent in others. Less calcification is generally seen in hand and foot bones. CT demonstrates matrix calcification much more sensitively than conventional radiography and is important for confirming chondroid nature.
Report Sentence
Arcs and rings pattern chondroid matrix calcification within a well-defined medullary lesion, consistent with enchondroma.
Enchondroma does not produce significant endosteal scalloping of the inner cortical surface or shows minimal scalloping (<2/3 of cortical thickness). This finding is one of the most important CT criteria for distinction from chondrosarcoma. Scalloping depth not exceeding 2/3 of cortical thickness and scalloping length not exceeding 2/3 of the lesion favors benignity. Cortical thinning is more commonly seen in hand/foot bones but almost all lesions are benign at this location.
Report Sentence
No significant endosteal scalloping of the cortex adjacent to the lesion, consistent with benign enchondroma.
Enchondroma shows markedly high signal on T2-weighted sequences — due to 70-80% water content of hyaline cartilage. Lobular structure may be observed on T2 as bright lobules with intervening thin low-signal septa. Calcified areas show low signal on all sequences. T2 signal intensity is similar to chondrosarcoma — distinction is made by enhancement pattern and clinical findings.
Report Sentence
Intramedullary lobular lesion with markedly high T2 signal, consistent with chondroid matrix-producing lesion.
Enchondroma shows low-to-intermediate signal intensity on T1-weighted sequences. High T1 signal of normal fatty bone marrow is replaced by cartilage tissue. Well-defined borders of the lesion and sharp boundary with surrounding normal bone marrow favor benignity.
Report Sentence
Well-defined intramedullary lesion with low-to-intermediate signal intensity on T1-weighted sequences.
Enchondroma shows no or minimal peripheral/septal enhancement on post-gadolinium sequences. This finding is the most critical MRI finding for enchondroma-chondrosarcoma distinction. While chondrosarcoma shows prominent ring-and-arc pattern septal enhancement, enchondroma has no or very mild enhancement. Presence and degree of enhancement is an important indicator of tumor grading.
Report Sentence
The lesion shows no/minimal enhancement on post-contrast sequences, consistent with benign enchondroma; prominent enhancement should be considered in favor of malignancy.
No significant diffusion restriction is seen in enchondroma on DWI. ADC values are high — the high water content of hyaline cartilage allows free diffusion. In chondrosarcomas (especially high-grade), diffusion restriction becomes prominent as cellularity increases and ADC values decrease. DWI/ADC provides complementary information to enhancement pattern in enchondroma-chondrosarcoma distinction.
Report Sentence
No significant diffusion restriction on DWI with high ADC values, consistent with benign enchondroma.
Criteria
Single lesion. Most common form. In hand/foot bones or long bone metaphysis. Very low malignant transformation risk (<1%). Asymptomatic, incidental.
Distinct Features
Well-defined, chondroid matrix calcification, no or minimal endosteal scalloping, no enhancement, stable size. Less calcification and more prominent cortical expansion are generally seen in hand/foot bones.
Criteria
Multiple enchondromas. Non-hereditary, sporadic. Usually unilateral predominance. Malignant transformation risk 25-50% (much higher than solitary). Bone deformities and short stature.
Distinct Features
Enchondromas in multiple bones, usually with unilateral predominance. Metacarpals and phalanges are most commonly affected. Growth deformities (shortening, bowing). Each lesion should be monitored individually for malignancy — pain, growth, or calcification change is a warning sign.
Criteria
Multiple enchondromas + soft tissue hemangiomas (spindle cell hemangioma). Non-hereditary. Malignant transformation risk 25-100% (very high). Risk of bone and vascular malignancy.
Distinct Features
Multiple enchondromas (Ollier-like) + characteristic soft tissue hemangiomas (with phleboliths). On MRI, hemangiomas appear as lobular masses with high T2, low T1 signal, and low signal foci due to phleboliths. Aggressive follow-up is mandatory due to very high malignant transformation risk.
Distinguishing Feature
Chondrosarcoma shows endosteal scalloping >2/3, size >5 cm, ring-and-arc enhancement, pain and growth. Enchondroma shows no/<2/3 endosteal scalloping, stable size, no/minimal enhancement, asymptomatic. Distinction may be difficult in long bones — clinical correlation is critical.
Distinguishing Feature
Simple bone cyst is a homogeneous cystic lesion at fluid density without chondroid matrix calcification. Enchondroma shows chondroid matrix calcification and cartilage-specific high T2 signal on MRI.
Distinguishing Feature
Fibrous dysplasia appears as an intramedullary lesion with ground glass density, does not show arcs and rings calcification. Enchondroma shows arcs and rings calcification specific to chondroid matrix. On MRI, fibrous dysplasia shows low-to-intermediate T2 signal, enchondroma shows markedly high T2 signal.
Distinguishing Feature
Vertebral hemangioma shows high T1 signal due to fat content (T1 is low in enchondroma). Polka-dot pattern on CT is characteristic in vertebrae. Enchondroma shows chondroid matrix and high T2 signal, does not show fat signal on T1.
Urgency
lowManagement
Asemptomatik soliter enkondromlar tedavi gerektirmez ve izleme alınır. Patolojik fraktür riski olan veya semptomatik lezyonlarda küretaj + greftleme yapılır. Malignite şüphesinde (ağrı, büyüme, endosteal scalloping artışı) biyopsi veya geniş rezeksiyon uygulanır.Biopsy
Not NeededFollow-up
Soliter asemptomatik enkondrom genellikle izlem gerektirmez. Şüpheli bulgular varsa (uzun kemik yerleşimi, sınırda boyut, minimal scalloping) 6-12 ayda bir MR ile boyut ve kontrastlanma paterni izlenir. Ollier/Maffucci hastalarında düzenli tüm vücut tarama önerilir — her lezyonda ağrı, büyüme veya kalsifikasyon değişikliği malignite uyarısıdır.Enchondroma is generally benign and treatment is not needed in most cases. Enchondromas in hand and foot bones are almost always benign. In long bone lesions, enchondroma-chondrosarcoma distinction is the most important clinical issue — endosteal scalloping, enhancement, size change, pain, and calcification irregularity are critical parameters. Malignant transformation risk is very high in Ollier disease (25-50%) and Maffucci syndrome (25-100%), and regular screening is mandatory.
Enchondroma is mostly asymptomatic and incidentally discovered. Malignant transformation risk is very low in hand/foot bones, slightly higher in axial skeleton. Ollier disease (multiple enchondromas) and Maffucci syndrome (enchondromas + soft tissue hemangiomas) carry higher malignant transformation risk (25-30%).