Osteochondroma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]
Overview
Osteochondroma arises from the cartilage cells (chondrocytes), which are normally involved in the mechanical support of the bone. The pathogenesis of osteochondroma consists of abnormal outgrowth of bone and cartilage, associated with the aberrant development of the growth plate.[1] Genes involved in the pathogenesis of osteochondroma include EXT1 and EXT2 genes. Osteochondroma is associated with a number of syndromes that include Langer-Giedion syndrome, Potocki-Shaffer syndrome, and metachondromatosis syndrome. On gross pathology, osteochondromas have a "mushroom-like shape", the tumor size ranges from 1 to 2 cm, and they are normally located in the metaphysial region of the affected bone.[2] On microscopic histopathological analysis, osteochondroma shows cartilage cells growing in columns with a lobular arrangement.[3]
Pathogenesis
- Osteochondroma arises from the cartilage cells (chondrocytes), which are normally involved in the mechanical support of the bone.
- The pathogenesis of osteochondroma consists of abnormal outgrowth of bone and cartilage, associated with the aberrant development of the growth plate.[3]
- A hallmark feature of osteochondromas is that they grow independently, without an associated epiphysis, usually away from the nearby joint.[4]
- As the osteochondroma cartilage grows, it forms a cap over a bony mass that develops by progressive enchondral ossification.[5]
- The bony portion of the osteochondroma contains mature, cortical and medullary bone with a marrow space contiguous with the parent bone.
- Osteochondromas have their own growth plate and stop growing with skeletal maturity.
- Osteochondroma usually presents as a solitary cartilage-capped bony outgrowth protruding from the bone surface in the metaphysis.
- Osteochondroma is usually located in the metaphyseal region of the long bones. Common anatomical locations include: the femur, the proximal tibia, and the proximal humerus. These locations account for 65-85% of cases.[5]
- Osteochondroma is a slow growing tumor which may transform malignant after time.
Genetics
- Development of osteochondroma is the result of multiple genetic mutations.
- Genes involved in the pathogenesis of osteochondroma include:[6]
- Germ line mutation EXT1 - chromosome 8q24.11-q24.13
- Germ line mutation EXT2 - chromosome 11p11-12
Associated Conditions
- Osteochondroma is associated with a number of syndromes that include:[1]
- Langer-Giedion syndrome
- Potocki-Shaffer syndrome
- Metachondromatosis syndrome
Gross Pathology
- On gross pathology, osteochondroma is an irregular mass with a "mushroom-like shape", a bluish gray cap of cartilage, and usually located in the metaphysial region of the affected bone.
- Other gross pathology findings, include:[2]
- Tumoral size ranges from 1 to 2 cm.
- Opaque yellow cartilage with calcification in the matrix.
- The base of the lesion has a rim of cortical bone and central cancellous bone.
- The cartilage cap is usually thin (1-6 mm); irregular and thick cap (> 2 cm) may be indicative of malignant transformation.
Microscopic Pathology
- On microscopic histopathological analysis, the characteristic feature of osteochondromas is the presence of cartilage-like extracellular tumor matrix.[3]
- Other histopathological features of osteochondroma, include:
- The presence of cartilage cells growing in columns with a lobular arrangement.[3]
- Mild atypia with nuclear enlargement.
- The perichondrium demonstrates a thin layer of cells with higher cellular density than cartilage.
Gallery
![Bone - Osteochondroma[2]](/index.php/File:Osteochondroma_5_micropathology.jpeg)
![Bone - Osteochondroma[2]](/index.php/File:Osteochondroma_3_micropathology.jpeg)
![Bone - Osteochondroma[2]](/index.php/File:Osteochondroma_2_micropathology.jpeg)
![Bone - Osteochondroma[2]](/index.php/File:Bone_osteochondroma1_micropathology.jpeg)
References
- ↑ 1.0 1.1 Kitsoulis P, Galani V, Stefanaki K, Paraskevas G, Karatzias G, Agnantis NJ, Bai M (2008). "Osteochondromas: review of the clinical, radiological and pathological features". In Vivo (Athens, Greece). 22 (5): 633–46. PMID 18853760.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Osteochondroma. Libre Pathology. http://librepathology.org/wiki/index.php/Osteochondroma Accessed on January 27, 2015
- ↑ 3.0 3.1 3.2 3.3 {{cite journal |vauthors=Porter DE, Simpson AH |title=The neoplastic pathogenesis of solitary and multiple osteochondromas |journal=The Journal of Pathology |volume=188 |issue=2 |pages=119–25 |year=1999 |pmid=10398153 |doi=10.1002/(SICI)1096-9896(199906)188:2<119::AID-PATH321>3.0.CO;2-N |url=http://dx.doi.org/10.1002/(SICI)1096-9896(199906)188:2
- ↑ Osteochondroma. Dr Yuranga Weerakkody. Radiopedia. http://radiopaedia.org/articles/osteochondroma Accessed on January 28, 2016
- ↑ 5.0 5.1 Diagnostic Radiology: Musculoskeletal Imaging: Osteochondroma. WikiBooks.(2015) https://en.wikibooks.org/wiki/Diagnostic_Radiology/Musculoskeletal_Imaging/Tumors_Basic/Osteochondroma Accessed on January 28, 2016
- ↑ Judith VMG Bovée. Multiple Osteochondromas: Review. Orphanet Journal of Rare Diseases. Biomed Central http://ojrd.biomedcentral.com/articles/10.1186/1750-1172-3-3 Accessed on January 27, 2016