History: 17 year old female. History withheld.
This is a case of osteogenesis imperfecta. Osteogenesis imperfecta is a genetic defect in forming type 1 collagen. There are multiple subtypes of osteogenesis imperfecta, which are divided according to the Silence classificaiton system as follows:
Type 1 – Autosomal Dominant, blue sclerae, mildest form (often called osteogenesis imperfecta tarda), 50% will have hearing loss
Type 2 – Autosomal Recessive, blue sclerae, lethal in perinatal period
Type 3 – Autosomal Recessive, normal sclerae, fractures at birth, most severe form that is non lethal.
Type 4 – Autosomal Dominant, normal sclerae, moderate deformities, normal hearing
There are more complex classification characteristics that have been added since the Silence classification system originally was published. Those can be read about here.
The interesting finding on the image above is what is called gracile (meaning slender) diaphyses. The differential diagnosis of gracile diaphyses is as follows:
1. Paralysis or disuse
2. Juvenile idiopathic arthritis
4. Marfan Syndrome
6. Osteogenesis imperfecta
7. Muscular Dystrophy
There are many more rare entities that cause gracile diaphyses which aren’t worth mentioning.
Read about basilar invagination in a patient with osteogenesis imperfecta.
Read about cochlear otosclerosis in a patient with osteogenesis imperfecta.