Enchondroma

Enchondroma is a type of benign (non-cancerous) bone tumor that originates in the cartilage, the flexible tissue that cushions joints and lines the ends of bones. These tumors most commonly develop inside the small bones of the hands and feet, although they can also occur in the long bones of the arms, legs, and ribs (1). While enchondromas are not cancerous, they can weaken the bone, leading to fractures, deformities, or pain.

Enchondromas are typically diagnosed during childhood or adolescence when bones are still growing, but they can persist into adulthood. In many cases, they are discovered incidentally during imaging tests for unrelated conditions. Because they rarely transform into malignant tumors, they are generally considered low-risk; however, careful monitoring and proper management are essential to avoid complications.

Symptoms

Most enchondromas do not cause symptoms and may remain unnoticed for years. When symptoms do occur, they often depend on the size and location of the tumor. Common signs include:

• Pain: Although enchondromas are usually painless, pain may develop if the tumor weakens the bone enough to cause a fracture or if it irritates nearby tissues (1).
• Swelling: Visible swelling or a palpable lump may develop, particularly in small bones of the hand or foot.
• Fractures: One of the most common ways enchondromas are discovered is after a bone breaks easily due to tumor-induced weakening.
• Restricted movement: In cases where enchondromas are near joints, they may cause stiffness, reduced range of motion, or discomfort during movement.
• Bone deformities: Multiple enchondromas or large tumors may cause visible deformities in the affected area.

Because the symptoms often overlap with other bone conditions, proper evaluation is essential for accurate diagnosis (2).

Causes

The exact cause of enchondromas is not fully understood. However, they are believed to arise due to abnormal growth of cartilage cells within the bone marrow cavity. Instead of developing normally into bone tissue, some cartilage persists and grows abnormally, leading to the formation of the tumor (2).

In most cases, enchondromas are isolated and not linked to any underlying genetic condition. However, some are associated with rare syndromes that involve multiple tumors, including

• Ollier’s disease: A condition characterized by multiple enchondromas that can affect growth and cause bone deformities.
• Maffucci syndrome: A rare disorder where multiple enchondromas occur along with benign vascular tumors called hemangiomas.

Both conditions carry an increased risk of malignant transformation compared to solitary enchondromas.

Risk Factors

Certain factors may increase the likelihood of developing enchondromas (2):

• Age: They are most often diagnosed in children and young adults, especially during periods of rapid bone growth.
• Genetic syndromes: People with Ollier’s disease or Maffucci syndrome have a higher risk.
• Location in small bones: Enchondromas are more common in the hands and feet than in larger bones.
• Family history: Though most cases are sporadic, some inherited tendencies may play a role.

While these factors increase susceptibility, enchondromas can occur in anyone, even without known risk factors.

Diagnosis

Diagnosing enchondroma often involves a combination of medical history, physical examination, and imaging studies. Because the condition is frequently asymptomatic, many are found incidentally during X-rays for other issues.

Common diagnostic methods include

• X-ray: The primary imaging tool that often reveals a well-defined, oval-shaped lesion within the bone.
• MRI (Magnetic Resonance Imaging): Provides detailed images of the tumor’s size, structure, and relationship to nearby tissues.
• CT scan (Computed Tomography): Helpful in assessing bone involvement and ruling out malignancy (2).
• Bone scan: Sometimes used to detect multiple lesions or to distinguish benign from malignant growths.
• Biopsy: In cases where cancer is suspected, a tissue sample may be taken to confirm the diagnosis under a microscope (3).

A critical part of diagnosis is ruling out chondrosarcoma, a malignant cartilage tumor. While rare, enchondromas can sometimes transform into this type of cancer, making careful evaluation important.

Treatment Options

The treatment approach for enchondromas depends on factors such as the tumor’s size, location, symptoms, and whether it is solitary or part of a syndrome (2).

• Observation and Monitoring

• If the enchondroma is small, asymptomatic, and discovered incidentally, doctors may recommend periodic observation.
• Regular imaging (X-rays or MRIs) ensures the tumor does not grow or cause complications.

• Surgical Treatment
  Surgery may be necessary if the tumor causes pain, weakens the bone, or leads to fractures. Options include

• Curettage: The most common procedure, where the surgeon scrapes out the tumor from the bone cavity (3).
• Bone grafting: After curettage, the cavity may be filled with bone graft material to strengthen the bone.
• Internal fixation: Metal plates, screws, or rods may be used if the bone is unstable or fractured.

• Management of Complications

• Fractures caused by enchondromas are treated with standard fracture care, which may include casting, bracing, or surgery.
• In syndromic cases, regular monitoring is crucial to detect early signs of malignant transformation.

Living With or Prevention

There is no known way to prevent enchondromas, as they are not directly linked to lifestyle or environmental factors (3). However, individuals living with this condition can take certain measures to ensure good bone health and minimize complications

• Regular follow-ups: Patients should adhere to scheduled imaging and doctor visits to monitor tumor growth.
• Bone protection: Avoiding high-impact activities that increase fracture risk is often recommended.
• Healthy lifestyle: Maintaining strong bones through a diet rich in calcium and vitamin D, along with regular weight-bearing exercise, supports overall skeletal health.
• Awareness of symptoms:  Pain, swelling, or sudden fractures should prompt immediate medical evaluation.

For individuals with multiple enchondromas or related syndromes, long-term monitoring is essential. While malignant transformation is rare, early detection greatly improves outcomes if it occurs.

References

1. Lui TH, Harries RJ. Endoscopic Curettage and Bone Grafting of Enchondroma of the Metacarpal Head. Arthrosc Tech. 2025 May 24;14(7):103618. doi: 10.1016/j.eats.2025.103618. PMID: 40822199; PMCID: PMC12350217.
2. Xiang X, Cheng S, Yang YJ, Qiu L. Ultrasound manifestations of enchondroma protuberans: Two case reports. Medicine (Baltimore). 2018 Jun;97(25):e11161. doi: 10.1097/MD.0000000000011161. PMID: 29924025; PMCID: PMC6023666.
3. Fang S, Liu L, Zhang M, Pan N, Gao W, Pan J, Liu J. Primary soft tissue chondroma of the posterior mediastinum: a rare case report and literature review. J Int Med Res. 2021 Oct;49(10):3000605211053557. doi: 10.1177/03000605211053557. PMID: 34686095; PMCID: PMC8544772.