Metachondromatosis

Alternate names

METCDS

Definition

Metachondromatosis (MC) is a rare bone disorder characterized by the presence of both multiple enchondromas and osteochondroma-like lesions.

Cause

The condition has been linked to mutations in the PTPN11 gene in several families.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

It is inherited in an autosomal dominant manner.

Onset

The first signs occur during the first decade of life.

Signs and symptoms

• Metachondromatosis (MC) is characterized by the presence of both multiple enchondromas and osteochondromas.
• Enchondromas are benign (noncancerous) tumors that appear on the inside of the bone.
• Those that are associated MC typically involve the iliac crests (part of the pelvis) and metaphyses of long bones, particularly the proximal femur (portion of the thigh bone closer to the trunk).
• These tumors are usually painless, but when they appear in the hands or feet, or in multiple lesions (as is typical in MC), they can deform the bone.
• Osteochondromas are also benign tumors. These form on the surface of the bone near the growth plates (areas of developing cartilage tissue near the ends of long bones in children) and are made up of both bone and cartilage. Osteochondromas may grow as the affected child grows, and stop growing when the child reaches skeletal maturity.
• They have a tendency to regress or disappear after the first or second decade of life.
• Those that are associated with MC most frequently occur in the small bones of the hands and feet, predominantly in digits and toes.
• The characteristic location and orientation of these in individuals with MC (as well as lack of bone shortening and short stature) are what generally differentiate MC from hereditary multiple osteochondromas (HMO), a disorder with overlapping features.
• The osteochondromas of MC point toward the joint to which they are adjacent (whereas those of HMO point away).
• Osteochondromas often cause painless bumps, but pain or other discomfort may occur if the tumors put pressure on soft tissues, nerves, or blood vessels.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Abnormality of epiphysis morphology(Abnormal shape of end part of bone)
• Abnormality of the metaphysis(Abnormality of the wide portion of a long bone)
• Avascular necrosis(Death of bone due to decreased blood supply)
• Bone pain
• Cranial nerve paralysis
• Exostoses(Formation of new noncancerous bone on top of existing bone)
• Multiple enchondromatosis

Diagnosis

• Diagnosis is made based on the distribution and orientation of lesions; however, a recently published case report describes a family with radiographic features of both metachondromatosis and MO, and a mutation of EXT-2..

External links

Classification	ICD-10: Q78.4 OMIM: 156250 DiseasesDB: 32116
External resources	Orphanet: 2499