Enchondroma: Symptoms, Types, Causes and Treatment

Enchondromas are among the most common benign bone tumors, originating from cartilage within the bone. While they may sound intimidating, most enchondromas are discovered incidentally and cause minimal symptoms. However, understanding their symptoms, types, causes, and treatment options can be vital—especially in cases where complications or rare syndromes are involved. In this article, we will explore enchondromas in detail, helping you recognize the signs, understand the underlying science, and appreciate available management strategies.

Symptoms of Enchondroma

Enchondromas often go unnoticed. Many people have these tumors without ever realizing it, as they can remain asymptomatic for years. When symptoms do emerge, they are usually related to the size and location of the tumor, or the presence of complications like fractures. Early recognition is key to ensuring the best outcomes, particularly when rare complications such as malignant transformation occur.

Symptom	Description	Frequency/Context	Source(s)
Pain	Dull, aching pain or tenderness	More common with larger lesions or fractures	1 11
Swelling	Visible mass or bulge	Fingers, hand, or affected bone	1 11
Pathological fracture	Bone breaks with minimal trauma	Often the first presentation, especially in the hand	11 1
Asymptomatic	No symptoms	Most common; often found incidentally	5 11

Table 1: Key Symptoms

Understanding the Clinical Presentation

Pain and Swelling

Most enchondromas are silent. However, when located in small bones of the hand or foot, or when they grow, they can cause:

• Dull pain or localized tenderness
• Swelling or a noticeable mass, especially in the fingers

Pain typically arises due to the tumor expanding and thinning the cortex of the bone, or if a fracture occurs through the weakened area 1 11.

Pathological Fracture

A pathological fracture—where a bone breaks due to minimal or no trauma—is a classic presentation, especially in hand enchondromas. In such cases, pain is usually sudden and severe, often prompting the patient to seek medical attention 1 11.

Asymptomatic Cases

It’s important to stress that most individuals with enchondromas experience no symptoms. These tumors are often detected incidentally on X-rays taken for unrelated reasons 5 11.

Rare Complications

In rare cases, enchondromas may cause:

• Skeletal deformity (especially in syndromic cases)
• Shortening of the affected bone
• Restricted joint movement due to tumor growth or deformity 9 8

Types of Enchondroma

Enchondromas are not a uniform entity. They can present as solitary lesions or as part of complex syndromes involving multiple tumors. Understanding these variations helps guide prognosis, surveillance, and treatment.

Type	Features/Location	Associated Syndromes/Complications	Source(s)
Solitary	Single lesion, most common	Rarely undergoes malignant transformation	5 11
Multiple (Enchondromatosis)	Several lesions, asymmetric	Ollier disease, Maffucci syndrome; ↑ risk of malignancy	2 4 8
Syndromic	Includes vascular, exostotic features	Maffucci syndrome (haemangiomas), Metachondromatosis (exostoses)	2 4 8

Table 2: Enchondroma Types

Solitary Enchondroma

• Most common form
• Usually affects the small bones of the hands and feet, but can occur in long bones
• Rarely transforms into cancer (chondrosarcoma) 5 11
• Detected incidentally or after a fracture

Multiple Enchondromas (Enchondromatosis)

Ollier Disease

• Characterized by multiple, asymmetrically distributed enchondromas
• Manifests in childhood
• Risk of skeletal deformities, limb length discrepancy, and malignant transformation (20–50%) 2 4 8

Maffucci Syndrome

• Multiple enchondromas plus soft tissue hemangiomas (benign vascular tumors)
• Increased risk of malignant transformation—not only to chondrosarcoma, but also non-skeletal tumors (e.g., gliomas, ovarian tumors) 4 8
• Very rare

Other Rare Syndromes

• Metachondromatosis: Both enchondromas and exostoses (bony outgrowths)
• Genochondromatosis, spondyloenchondrodysplasia, etc.: Extremely rare subtypes, often with distinct genetic or skeletal features 2 4

Distinguishing from Similar Conditions

• Multiple Hereditary Exostoses (MHE): Characterized by exostoses (outward-growing bone/cartilage tumors), not enchondromas (which grow within bone) 8 9
• Accurate diagnosis is crucial for prognosis and management

Causes of Enchondroma

The precise cause of solitary enchondromas remains uncertain, but recent research has shed light on several molecular and developmental factors, particularly in syndromic forms.

Cause/Factor	Mechanism / Description	Relevance/Notes	Source(s)
Genetic Mutations	IDH1/IDH2 mutations, PTHR1 mutations	Key in syndromic enchondromatosis	6 7 4
Disordered Growth Plate	Persistence of cartilage cells	Leads to cartilage islands within bone	6 7
Hedgehog Signaling	Overactive pathway	Promotes enchondroma development	2 7
Non-hereditary	Most solitary lesions	Environmental/unknown causes	8 9

Table 3: Causes and Mechanisms

Genetic and Molecular Factors

IDH1 and IDH2 Mutations

• Most multiple enchondromas (especially in Ollier disease and Maffucci syndrome) are linked to somatic mutations in IDH1 and IDH2 genes 6 4
• These mutations result in abnormal metabolism of cartilage cells, leading to tumor formation

PTHR1 Mutations and Hedgehog Pathway

• Mutations in the parathyroid hormone receptor 1 (PTHR1) gene lead to abnormal signaling, causing the persistence of growth plate cartilage and formation of enchondromas 7
• Overactivation of the hedgehog signaling pathway is a known driver of enchondroma development 2 7

Abnormal Growth Plate Regulation

• Normally, cartilage within the growth plate is replaced by bone during development
• In enchondromas, islands of cartilage remain, likely due to disrupted signaling, and can later proliferate 6 7
• This explains why enchondromas often arise near the metaphyses (ends) of long bones and in childhood 2 4

Hereditary Factors

• Most solitary enchondromas are not inherited
• Syndromic forms (e.g., Ollier, Maffucci) are generally sporadic, though rare familial cases have been reported 8 9

Environmental and Unknown Factors

• There is no strong evidence linking environmental exposures to enchondroma formation
• Most cases are considered to arise spontaneously 8 9

Treatment of Enchondroma

Management of enchondromas is highly individualized, depending on symptoms, tumor location, and risk of complications. Many cases require no intervention, but some need surgery, especially when symptoms or complications arise.

Treatment	Description	Indication / Outcome	Source(s)
Observation	Regular monitoring, no intervention	Asymptomatic, small, non-expanding lesions	5 11
Surgery (Curettage)	Removal of tumor via scraping	Symptomatic lesions, fractures, suspicion of malignancy	1 10 11
Bone Grafting / Bone Cement	Filling the cavity after curettage	Various materials (autograft, allograft, calcium phosphate, cement)	10 12 13 14
No Grafting	Simple curettage without filling	Effective in many hand lesions	12
Internal Fixation	Hardware for stabilization	Pathological fractures, large defects	14 13
Multidisciplinary Team	Combined expertise	Diagnosis and management of difficult cases	5

Table 4: Treatment Options

Observation

• Many enchondromas, especially those discovered incidentally and not causing symptoms, can simply be monitored with periodic X-rays
• No treatment is needed unless the tumor grows, becomes painful, or causes other issues 5 11

Surgical Curettage

• The mainstay for symptomatic lesions, those causing fractures, or if malignancy is suspected
• Involves surgically scraping out the tumor (curettage) 1 11
• Usually performed under regional or general anesthesia

Bone Grafting and Alternatives

• Traditionally, the cavity left after tumor removal was filled with bone grafts (autograft from the patient or allograft from a donor) 10
• Recent advances include use of injectable calcium phosphate cement or other bone substitutes, which provide stability and promote healing 1 13
• Some studies suggest that simple curettage alone (without bone grafting) is effective for many hand enchondromas 12

Internal Fixation and Cemented Hardware

• When a pathological fracture is present or the cavity is large, surgeons may use pins, plates, or bone cement to stabilize the bone 14 13
• This allows for early mobilization and functional recovery

Complications and Recurrence

• Surgical outcomes are generally excellent, with low recurrence rates (less than 10%) 1 11
• Infection is rare but can occur, sometimes requiring further intervention 1
• Malignant transformation is unusual, but patients with multiple enchondromas (Ollier, Maffucci) should be monitored more closely 4 11

The Role of a Multidisciplinary Team

• Differentiating benign enchondroma from low-grade chondrosarcoma can be challenging
• In complex cases, a team including orthopedic oncologists, radiologists, and pathologists is essential for accurate diagnosis and optimal treatment 5

Conclusion

Enchondromas are common benign cartilage tumors that are usually discovered incidentally and often require no treatment. However, understanding their symptoms, various types, underlying causes, and management options is crucial—especially in rare and syndromic cases. Here’s a summary of the key points:

• Symptoms are often absent, but can include pain, swelling, and fracture, especially in the hand and fingers.
• Types include solitary lesions and multiple forms (enchondromatosis), with syndromic variants like Ollier disease and Maffucci syndrome carrying higher risks of complications.
• Causes involve genetic mutations (IDH1/IDH2, PTHR1) and abnormal cartilage cell behavior, particularly in syndromic cases.
• Treatment ranges from observation to surgery; most solitary lesions can be managed conservatively, while symptomatic or complicated cases may require curettage, grafting, or hardware stabilization.
• Malignant transformation risk is low for solitary lesions, but higher in syndromic forms—necessitating careful follow-up.

Staying informed and seeking specialist care when needed ensures the best outcomes for those affected by enchondroma, whether solitary or part of a more complex syndrome.