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Developmental abnormalities


Reviewers: Dariusz Borys, M.D. (see Reviewers page)
Revised: 1 June 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.


Type I:
● Rare, lethal
● Extreme limb shortening
● Marked discrepancy between head and trunk size
● Severely delayed ossification

Type IA:
● Autosomal recessive
● No ossification of vertebral pedicles
● Rib fractures
● Chondrocytes have inclusion bodies, but cartilage matrix is near normal

Type IB:
● Distinctly abnormal cartilage matrix with rarefaction of ground substance and peculiar ringlike pericellular arrangement of collagen fibers
● Lethal osteochondrodysplasia due to mutations in transporter gene for diastrophic dysplasia sulfate
● Genetic defect causes complex derangement in cartilage matrix assembly
● Impaired decorin deposition causes lack of development of normal interterritorial matrix, preventing necessary structural substrate for proper endochondral bone formation and severe skeletal phenotype

Radiologic images

Short and abnormal long bones in fetus with type IB

Case reports

● Child with consanguineous (first cousins) parents and type IB (Arch Pathol Lab Med 2001;125:1375)

Gross images


Micro description

● Abnormal endochondral bone formation with curved cartilage-bone junction at growth plates, periosteal bony spurs
● Spongelike cartilage matrix due to lack of interterritorial matrix
● Epiphyseal cartilage composed of multiple discrete units of chondrocytes encased in territorial capsule and separated from each other by clefts containing fibroblast-like cells
● Mosaic of chondrocyte units (chondrons) due to breakdown of usual matrix continuity of epiphyseal cartilage

Micro images

Abnormal cartilage bone junction, abnormal matrix

Additional references


End of Bone > Developmental abnormalities > Achondrogenesis

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