Answer for BIR CoW 25 June 2023
Osteopetrosis
Findings:
Osteopetrosis is characterized by the classic "bone within bone" appearance, primarily observed in the short tubular bones of the hand.
Discussion:
Osteopetrosis, also known as Albers-Schönberg disease or Marble bone disease, can be classified into different types: Malignant (infantile) type (autosomal recessive), Benign (adult) type (autosomal dominant), Intermediate type (autosomal recessive), and Carbonic anhydrase isoenzyme type II deficiency (Sly disease).
Etiology:
Osteopetrosis is caused by abnormal osteoclast function, leading to an imbalance between bone formation and resorption. Bone production remains unaffected, resulting in the continuous production of bone that cannot be remodeled. This leads to hyperostosis, the inability to create a medullary space at the endosteum, diffuse sclerotic bones, increased susceptibility to fractures, and poor fracture healing.
Types:
1. Infantile type:
- Symptoms include failure to thrive, growth retardation, and cranial nerve deficits, especially poor vision.
2. Adult types:
a) Type 1 (skull base and spine spared):
- Often incidentally found
- May exhibit pain and fractures
b) Type 2 (cranium spared):
- Often incidentally found
- May exhibit pain and fractures
3. Intermediate types:
- Variable manifestations and severity
- Features include short stature, mandible osteomyelitis (especially in adult types), fractures (especially in adult types), abnormal dentition, dental caries, frontal bossing, hematologic deficiencies due to lack of marrow, anemia, thrombocytopenia, leukopenia, hepatosplenomegaly, extramedullary hematopoiesis, hypocalcemia, blindness, deafness, facial nerve palsy, stroke, and renal tubular acidosis.
Characteristic Findings:
- Uniformly dense and sclerotic bones with smooth margins and no irregular periosteal new bone.
- Loss of normal corticomedullary differentiation.
- Splaying of metaphyses, most prominent in the distal femur.
- Manifestation of defective osteoclasts unable to remodel bone, leading to Erlenmeyer flask deformity.
- Diffuse thickening and sclerosis with loss of diploic space in the skull.
- Hyperostosis and sclerosis of the skull base.
- "Bone within bone" appearance as a manifestation of the inability to remodel bone.
MRI Findings:
- Primarily used to assess the degree of marrow involvement and response to therapy.
- Other findings may include hydrocephalus secondary to aqueduct stenosis, optic nerve atrophy, tonsillar ectopia, and ventriculomegaly.
Differential Diagnosis:
- Heavy metal poisoning
- Melorheostosis (limited to one extremity)
- Hypervitaminosis D
- Pyknodysostosis
- Fibrous dysplasia of the skull/face
References:
1. Stark Z., Savarirayan R. Osteopetrosis. Orphanet. J. Rare Dis. 2009;4:5. doi: 10.1186/1750-1172-4-5.
2. Bailey J.R., Tapscott D.C. StatPearls. Treasure Island. StatPearls Publishing; Treasure Island, FL, USA: 2022. Osteopetrosis.
3. Albers-Schönberg H.E. Rontgenbilder einer seltenen Knockenerkrankung. Munch Med. Wochens
Findings:
Osteopetrosis is characterized by the classic "bone within bone" appearance, primarily observed in the short tubular bones of the hand.
Discussion:
Osteopetrosis, also known as Albers-Schönberg disease or Marble bone disease, can be classified into different types: Malignant (infantile) type (autosomal recessive), Benign (adult) type (autosomal dominant), Intermediate type (autosomal recessive), and Carbonic anhydrase isoenzyme type II deficiency (Sly disease).
Etiology:
Osteopetrosis is caused by abnormal osteoclast function, leading to an imbalance between bone formation and resorption. Bone production remains unaffected, resulting in the continuous production of bone that cannot be remodeled. This leads to hyperostosis, the inability to create a medullary space at the endosteum, diffuse sclerotic bones, increased susceptibility to fractures, and poor fracture healing.
Types:
1. Infantile type:
- Symptoms include failure to thrive, growth retardation, and cranial nerve deficits, especially poor vision.
2. Adult types:
a) Type 1 (skull base and spine spared):
- Often incidentally found
- May exhibit pain and fractures
b) Type 2 (cranium spared):
- Often incidentally found
- May exhibit pain and fractures
3. Intermediate types:
- Variable manifestations and severity
- Features include short stature, mandible osteomyelitis (especially in adult types), fractures (especially in adult types), abnormal dentition, dental caries, frontal bossing, hematologic deficiencies due to lack of marrow, anemia, thrombocytopenia, leukopenia, hepatosplenomegaly, extramedullary hematopoiesis, hypocalcemia, blindness, deafness, facial nerve palsy, stroke, and renal tubular acidosis.
Characteristic Findings:
- Uniformly dense and sclerotic bones with smooth margins and no irregular periosteal new bone.
- Loss of normal corticomedullary differentiation.
- Splaying of metaphyses, most prominent in the distal femur.
- Manifestation of defective osteoclasts unable to remodel bone, leading to Erlenmeyer flask deformity.
- Diffuse thickening and sclerosis with loss of diploic space in the skull.
- Hyperostosis and sclerosis of the skull base.
- "Bone within bone" appearance as a manifestation of the inability to remodel bone.
MRI Findings:
- Primarily used to assess the degree of marrow involvement and response to therapy.
- Other findings may include hydrocephalus secondary to aqueduct stenosis, optic nerve atrophy, tonsillar ectopia, and ventriculomegaly.
Differential Diagnosis:
- Heavy metal poisoning
- Melorheostosis (limited to one extremity)
- Hypervitaminosis D
- Pyknodysostosis
- Fibrous dysplasia of the skull/face
References:
1. Stark Z., Savarirayan R. Osteopetrosis. Orphanet. J. Rare Dis. 2009;4:5. doi: 10.1186/1750-1172-4-5.
2. Bailey J.R., Tapscott D.C. StatPearls. Treasure Island. StatPearls Publishing; Treasure Island, FL, USA: 2022. Osteopetrosis.
3. Albers-Schönberg H.E. Rontgenbilder einer seltenen Knockenerkrankung. Munch Med. Wochens
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!