Multiple hereditary exostoses

Case Discussion

Osteochondromatosis is an autosomal dominant disease with variable penetrance, characterized by the development of two or more osteochondromas that are benign cartilaginous tumors, located mainly in the metaphysis of long bones.
It is more frequent in men, who seem to have more severe manifestations.
The diagnosis is usually made in childhood by palpable mass or deformity with angulation.
Osteochondromas can be sessile or pediculate, usually bilateral and symmetrical.
Its most common locations are the proximal or distal femur, proximal humerus, distal radius, pelvis, and scapula. They are particularly frequent around the knee where it is more likely to suffer malignant degeneration. Facial bones are not affected.
Its radiological findings are metaphyseal widening, multiple sessile, or pedicle excrescences attached to the bone cortex.
Magnetic resonance is useful for estimating the cartilaginous cap that covers the osteochondroma,
Malignant transformation to chondrosarcoma should be suspected if an osteochondroma becomes symptomatic or grows rapidly. From the radiological point of view: the cartilaginous cap measures more than 1.5-2 cm in an adult (2-3 cm child), deflected edges, calcified foci in the cartilage, soft tissue mass with irregular calcifications, and sudden increase in uptake in the bone scan of an adult.
Differential diagnosis: Metachondromatosis, hemimelic epiphyseal dysplasia, Ollier disease.