An exostosis, also known as a osteochondroma, is a benign chondrogenic lesions derived from aberrant cartilage from the perichondral ring. Exostoses can cause chronic pain ranging from mild to moderate, but rarely severe, depending on the shape, size, and location of the lesion, though most are asymptomatic and are found serendipitously on plain x-ray taken for other reasons. It is most commonly found in pre-teens through early 20s adjacent to the physes of the distal femur and proximal tibia but can be found adjacent to other physes, most notably the distal phalanx of the finger, where it presents as a subungual mass. larger growths can occur on places like the ankles, knees, shoulders, elbows and hips. Very rarely are they on the skull.Though rare, malignant transformation can occur into a chondrosarcoma. They normally form growing stalks angling away from the physis toward the mid shaft of a long bone. When used in the phrases "cartilaginous exostosis" or "osteocartilaginous exostosis", the term is considered synonymous with

osteochondroma Osteochondroma is the most common benign tumor of bone. The tumors take the form of cartilage-capped bony projections or outgrowth on the surface of bones ( exostoses). It is characterized as a type of overgrowth that can occur in any bone where ...

. Some sources consider the two terms to mean the same thing even without qualifiers, but this interpretation is not universal.

Osteophytes

Osteophyte Osteophytes are Exostosis, exostoses (bony projections) that form along joint margins. They are distinct from enthesophytes, which are bone, bony projections that form at the attachment of a tendon or ligament. Osteophytes are not always distingui ...

s are bone spurs that develop on the margins of joints secondary to external stimuli such as

osteoarthritis Osteoarthritis is a type of degenerative joint disease that results from breakdown of articular cartilage, joint cartilage and underlying bone. A form of arthritis, it is believed to be the fourth leading cause of disability in the world, affect ...

. These are in no way related to exostoses.

Fossil record

Evidence for exostosis found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury. Exostosis has been reported in dinosaur fossils from several species, including '' Acrocanthosaurus atokensis'', ''

Albertosaurus sarcophagus ''Albertosaurus'' (; meaning "Alberta lizard") is a genus of large tyrannosaurid theropod dinosaur that lived in northwestern North America during the early to middle Maastrichtian age of the Late Cretaceous period, about 71 million yea ...

'', ''

Allosaurus fragilis ''Allosaurus'' ( ) is an extinct genus of theropoda, theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic Geologic time scale, period (Kimmeridgian to late Tithonian Geologic time scale, ages). The first fossil ...

'', ''

Gorgosaurus libratus ''Gorgosaurus'' ( ; ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period (geology), Period (Campanian), between about 76.5 and 75 million years ago. Fossil remains have been ...

'', and '' Poekilopleuron bucklandii''.

Hereditary multiple exostoses

Hereditary multiple exostoses Hereditary multiple osteochondromas (HMO), also known as hereditary multiple exostoses, is a disorder characterized by the development of multiple benign osteocartilaginous masses (exostosis, exostoses) in relation to the ends of long bones of t ...

(HME), also called hereditary multiple osteochondromas (HMO), is a condition that is estimated to affect 1 in 50,000 individuals. Multiple benign or noncancerous bone tumors develop in the affected individuals. The number and location vary among affected patients. Most people seem unaffected at birth; however, by the age of 12 years, they develop multiple exostoses. Affected individuals commonly complain of palpable and recognizable lumps (exostoses) at about the knees and in the forearms. The condition characteristically occurs bilaterally. It may lead to mild degrees of growth retardation and limb asymmetry.

Genu valgum Genu valgum, commonly called "knock-knee", is a condition in which the knees angle in and touch each other when the human leg, legs are straightened. Individuals with severe valgus deformity, valgus deformities are typically unable to touch thei ...

(commonly known as "knock-knees"), ankle valgus, and bowing and shortening of one or both of the forearm bones are common manifestations.

Types

* Buccal exostosis * Footballer's ankle (exotosis of the ankle bone) *

(HME) * Subungual exostosis * Surfer's ear (exostosis of the ear canal) * Torus mandibularis *

Torus palatinus A torus palatinus (: tori palatini), or palatal torus (: palatal tori), is a bony protrusion on the palate. Palatal tori are usually present on the midline of the hard palate.Neville, B.W., D. Damm, C. Allen, J. Bouquot. ''Oral & Maxillofacial P ...

Calcaneal spur A calcaneal spur (also known as a heel spur) is a bony outgrowth from the calcaneal tuberosity (heel bone). Calcaneal spurs are typically detected by x-ray examination. It is a form of exostosis. When a foot is exposed to constant stress, calc ...

(heel spur)

References

External links