Enchondroma

Generality

Enchondroma is a benign bone tumor that originates from a cartilage cell present within the bone marrow.
Like any tumor, enchondroma also arises as a result of some mutational events, which alter the cellular DNA. At the moment, despite the numerous studies on the subject, the precise factors that trigger the aforementioned mutational events are not clear.

Image from orthoinfo.aaos.org

Generally, enchondroma is characterized by the presence of a cyst which, in some patients, is responsible for fractures and bone deformities. Sometimes, this cyst assumes the characteristics of a malignant neoplasm, becoming, to be precise, a chondrosarcoma.
For a correct diagnosis of enchondroma, the following are essential: physical examination, medical history, diagnostic imaging tests and tumor biopsy.
If enchondroma is asymptomatic, it requires no treatment; if it is symptomatic, surgery is required.

Brief review of what a tumor is

In medicine, the terms tumor and neoplasia identify a mass of very active cells, capable of dividing and growing in an uncontrolled way.

• We speak of a benign tumor when the growth of the cell mass is not infiltrative (that is, it does not invade the surrounding tissues) and not even metastasizing.
• We speak of a malignant tumor when the abnormal mass of cells has the ability to grow very quickly and spread to surrounding tissues and the rest of the body.
  The terms malignant tumor, cancer and malignant neoplasm are to be considered synonymous.

What is enchondroma?

Enchondroma is a benign bone tumor that originates in a cartilage cell within the bone marrow.
According to another definition, enchondroma is a benign bone tumor, originating in the medullary cartilage; medullary cartilage is none other than the cartilage tissue located within the bone marrow.
At the skeletal level, the most common sites of onset of enchondroma are: the bones of the hand, the bones of the feet, the femur (thigh bone), the tibia (one of the two leg bones) and the humerus (bone of the leg). arm).
In most cases, enchondroma appears as a single tumor; more rarely, it is characterized by the presence of multiple tumor masses.

According to some medical investigations, 50% of enchondromas involve the bones of the hands and feet.

The remaining percentage of cases would be divided into enchondromas involving the femur, tibia and humerus.

WHAT IS THE BONE MARROW?

The bone marrow is a soft tissue present in the internal cavity of some bones (femur, humerus, vertebrae, etc.). Its job is to produce blood cells, which are red blood cells (erythrocytes), white blood cells (leukocytes) and platelets (thrombocytes).
The process of producing blood cells is called hematopoiesis.

EPIDEMIOLOGY

Enchondroma is a neoplasm that mainly affects the population between the ages of 10 and 20; in other words, it is more common in adolescents and young adults.
According to some statistical surveys, enchondroma represents less than 5% of all bone tumors and just over 17% of all benign type bone tumors.

Causes

Most cancers - including enchondroma - arise from genetic DNA mutations that alter the cellular processes of growth, division and death.

Cancer cells grow and divide abnormally, at a higher than normal rate, so much so that, for these reasons, experts tend to define them with the terminology of "crazy cells".

WHAT HAPPENS IN AN ENCHONDROME?

Some researchers believe that enchondroma derives from an alteration of the growth process of the cartilage, located at the extremity of the bones; other scholars, however, are of the idea that enchondroma is the consequence of a persistent and abnormal growth of the cartilage embryonic.

WHAT FACTORS PROMOTE DNA MUTATIONS?

Doctors have not yet discovered precisely what factors and circumstances favor DNA mutations at the origin of enchondroma episodes.
The most recent studies have ruled out that the onset of enchondromas depends on some of the classic risk factors for bone cancer, such as:

• Exposure to ionizing radiation
• Exposure to certain pharmacological / chemical substances.

Symptoms and Complications

For further information: Enchondroma Symptoms

The cell mass that characterizes the episodes of enchondroma is a cartilage cyst, located inside the bone marrow.
Generally, enchondroma is an asymptomatic neoplasm, ie it does not cause symptoms; instead it tends to be responsible for a specific symptomatology when the tumor mass arises on a bone of the hand or foot, or when the neoplasm presents with multiple masses.
As regards the symptoms in the cases just mentioned, this consists of:

• Abnormal bone weakening;
• Deformation of the affected bone or bones;
• Ease of fractures.

SPECIAL ASSOCIATIONS

Image from radiologytutorials.com site

Enchondroma is often a solitary tumor.
However, in some rare cases, it is possible that it appears in association with two particular medical conditions, known as Ollier's syndrome and Maffucci's syndrome.

• Ollier syndrome: also known as enchondromatosis, it is characterized by the continuous formation of enchondromas in different parts of the body. It usually appears at a young age.
  The formation of enchondromas stops upon completion of skeletal maturation.
  People with Ollier's syndrome have a particular propensity for bone fractures and, in fractured bones, have severe deformities.
  Ollier's syndrome affects approximately one in every 100,000 people.
• Maffucci syndrome: it is a condition characterized by the simultaneous presence of multiple enchondromas and multiple hemangiomas. Sometimes, it also involves the onset of multiple lymphangiomas.
  Generally, Maffucci syndrome occurs during adolescence or the years of puberty; it mainly affects the phalanges of the hand, causing them to deform and an unusual tendency to fracture. Rarely, it affects the phalanges of the feet and other skeletal areas.

COMPLICATIONS

Enchondroma is a benign neoplasm which, following further mutational DNA processes, can however become a malignant neoplasm. As a rule, the type of malignant tumor into which enchondroma converts is chondrosarcoma.
Fortunately, the conversion of an enchondroma to a chondrosarcoma is an uncommon event; according to some statistical surveys, it would occur in 5% of cases.
Unlike enchondroma, chondrosarcoma is responsible for various symptoms, including:

• Pain in the affected bone or bones;
• Pain more intense than usual upon awakening from night sleep or after particular activities;
• Swelling in the area presenting the tumor mass;
• Significant tendency to bone fractures.

Chondrosarcoma is a malignant bone tumor that affects the cartilage tissue located at the end of the skeletal bones.

Diagnosis

Almost always lacking a symptomatology, enchondroma is a condition that doctors almost always diagnose by chance, during an X-ray examination performed for other reasons (eg in the case of a bone injury or the presence of arthritis).
To know the characteristics of an enchondroma and to understand its actual danger, the following are essential: physical examination, anamnesis, further diagnostic imaging tests (in addition to X-rays) and tumor biopsy.

IMAGE DIAGNOSTICS

Imaging tests are primarily used to identify the exact location of the tumor mass.
The diagnostic imaging tests useful in case of bone cancer include:

• CT scan (or Computed Axial Tomography).
  Characteristics: it foresees the exposure of the patient to a certain amount of ionizing radiation, so it is slightly invasive.
• Nuclear magnetic resonance (NMR).
  Characteristics: it does not foresee the exposure of the patient to radiation, therefore it is not invasive.
• Bone scan.
  Characteristics: it involves the use of a radioactive contrast liquid, so it is invasive.

TUMOR BIOPSY

A tumor biopsy consists in taking and histological analysis, in the laboratory, of a sample of cells from the tumor mass.
It is the most appropriate examination to define the main characteristics of an enchondroma, from the precise histology to the degree of aggression.
Performed under local or general anesthesia, the removal of cells from an enchondroma can take place in at least two different ways: by means of a needle (bone needle biopsy) or by means of a scalpel ("open" biopsy).
To learn more about this topic, readers can consult the article here.

Importance of tumor biopsy in the presence of a suspected chondrosarcoma
Upon visual examination of the images provided by an MRI or CT scan, enchondroma and a low-grade chondrosarcoma exhibit very similar characteristics. This complicates their recognition.
The only way to understand the exact nature of the tumor is to subject it to a biopsy.

Treatment

If it lacks a symptomatology and maintains its benign nature, enchondroma does not require any treatment. In the aforementioned situations, the doctors' only indication is the recommendation to keep under observation and periodically monitor the tumor mass, through diagnostic imaging tests. (x-rays and more).

WHEN IS A TREATMENT NEEDED?

Enchondroma requires specific treatment when it is symptomatic (eg causes fractures, deformities, bone weakening, etc.) or when it changes into a malignant neoplasm.

WHAT DOES THE TREATMENT CONSIST OF?

The treatment of an enchondroma is surgical and consists, first, in the so-called scraping of the tumor mass and, subsequently, in the bone transplant:

• The curettage is an operation that the surgeon can perform only when the affected bone is intact. Therefore, if at the time of diagnosis of enchondroma there are fractures, it is necessary to wait for their healing.
• Bone transplantation consists in taking a piece of healthy bone tissue, from a part of the patient's own body, and grafting it into the affected area (autologous transplant or autotransplant). It serves to strengthen the bone just subjected to curettage.
  Sometimes, the transplant can be of the allogeneic type, that is, the removal involves a compatible donor.

PRE-OPERATIVE EVALUATIONS

Presence of symptoms and malignancy of the neoplasm aside, other aspects also affect the choice of surgery, including:

• The age of the patient;
• The general state of health of the patient;
• The patient's medical history;
• The extent of the disease;
• The patient's degree of tolerance to medications that may be needed during surgery;
• Patient preferences.

Prognosis

In most circumstances, enchondroma has a positive prognosis.
The cases that fail are usually those in which the enchondroma becomes a malignant neoplasm.