Bone islands are benign sclerotic areas in bone. They may be single or multiple.
Bone islands are typically noted incidentally on radiographs.
Lesions may be seen in patients from 7 to 78 years of age. There is no sex predilection.
The most common sites are the ribs, pelvis, and femora. Up to 32% may change in size.
Round, oval, or spiculated sclerotic areas are typically (66%) 0.5 to 1.5 cm.
Appearance is usually characteristic, although the differential diagnosis could include blastic metastasis, osteoma, osteoid osteoma, or infarct.
Other imaging studies are usually not required. Radionuclide bone scans are typically normal, but focal increased tracer can occur.
Magnetic resonance imaging (MRI) shows low signal intensity on T1- and T2-weighted sequences.
Osteopoikilosis is a sclerotic bone dysplasia presenting in childhood. It has been detected in all bones except the skull.
Lesions are smaller than typical bone islands (2 to 10 mm).
The condition is considered an autosomal dominant chondrodysplasia.
Lesions may grow in children, but stabilize or disappear in adults.
Most patients are asymptomatic, although 20% may present with joint pain.
Lesions are smaller and more well-defined than bone islands and involve the epiphysis and metaphysis.
Features are so characteristic that there is usually no difficulty in diagnosis.
Differential considerations include mastocytosis and tuberous sclerosis.
Radionuclide scans are typically normal but may be positive in growing lesions.
Osteopathia striata is a rare autosomal dominant inherited condition related to osteopoikilosis.
Patients are usually asymptomatic.
Distinct striations in the metaphysis of long bones parallel to the shaft. Striations may extend into the epiphysis.
Changes are usually bilateral.
The tibia is the most common site.
Radionuclide scans are normal.
Melorheostosis causes bone sclerosis involving one side of the cortex. The original description looked like dripping candle wax, thus the term “melorheostosis.”
Cause is unknown. Patients may be asymptomatic or present with pain in the involved region.
The condition may be present from birth to late adult life. In 50% of cases, the condition is evident by 20 years of age. There is no sex predilection.
The involved extremity may be shorter or, in some cases, longer. Muscle atrophy is also present in some cases.
The condition most commonly involves the long bones of the extremities. Most often it is unilateral.
Sclerosis and cortical thickening involve one side of the involved bone or bones. Typically, the process extends into the metaphysis or epiphysis, but soft tissue and joint involvement can occur. Associated conditions include:
Leg length discrepancy
FIGURE 14-4. Melorheostosis. Anteroposterior (AP) radiograph (A) and coronal reformatted computed tomography (CT) (B) images of the hand show irregular sclerosis and exuberant cortical thickening along the first ray.
Engelmann disease results in cortical thickening in the diaphysis of long bones progressing proximally and distally in the involved structure.
Most patients present in infancy or early childhood. It is an autosomal dominant inherited condition.
Neuromuscular dystrophy and malnutrition are associated with this condition.
Diaphyseal cortical thickening involving endosteal and periosteal surfaces
Normal epiphysis and metaphysis
Relative elongation of involved extremities
Differential diagnosis: chronic infection, infantile cortical hyperostosis, fibrous dysplasia
Cleidocranial dysplasia is an uncommon autosomal dominant disorder.
Patients present with delayed or incomplete cranial ossification and hypoplastic or aplastic clavicles. Delayed ossification may be evident in the axial skeleton and extremities.
The mandible may be large, and delayed tooth development is common.
Lack of midline ossification and wormian bones in the calvarium
Absent or hypoplastic clavicles
Delayed ossification in the spine, pelvis, and extremities
Femoral necks deformed or aplastic
Osteopetrosis is a disease of uncertain cause that leads to dense brittle bones.
There are multiple clinical forms of this condition.
Osteopetrosis infantile: autosomal recessive with failure to thrive, hepatosplenomegaly, cranial nerve dysfunction, blindness, and deafness. Death frequently occurs in early years of life.
Osteopetrosis tarda (delayed): autosomal dominant. Patients are usually asymptomatic. Detection results from mild anemia, cranial nerve palsies, or pathologic fractures.
Osteopetrosis intermediate: autosomal recessive with features between infantile and tarda in severity.
Infantile: uniformly dense sclerotic bones with changes similar to rickets near the growth plates
Tarda: bone-within-a-bone appearance
Intermediate: diffuse bone sclerosis, especially of the skull base. Bone-within-a-bone appearance. Avascular necrosis of the femoral heads.
FIGURE 14-8. Osteopetrosis intermediate. Anteroposterior (AP) radiograph of the tibia and femora shows bone sclerosis with bone-within-a-bone appearance in the epiphyses.
Mastocytosis is a systemic disease with mast cell accumulation in multiple organs affecting adult males and females.
Liver, spleen, lymph node, skeletal, and, most commonly, cutaneous organs are involved.
Patients present with skin lesions resembling urticaria pigmentosa, also diarrhea, vomiting, flushing, or intermittent shocklike episodes.
Radiographic features occur in 70% of patients:
Osteopenia and bone destruction most common in the skull, spine, and ribs
Osteosclerosis, which may resemble metastasis, Paget disease, or myelofibrosis
Features may be focal or diffuse.
Tuberous sclerosis is an autosomal dominant inherited disorder.
Characteristic features include seizure disorders, mental retardation, and cutaneous hamartomas.
Skull: foci of sclerosis and trabecular prominence; calvarial thickening; intercerebral calcifications; brain lesions in ventricles, white matter, and cortex 50% to 80%.
Axial/appendicular skeleton: focal or diffuse cystlike lesions or areas of sclerosis. Subperiosteal and cortical lesions result in irregular cortical appearance.
Extraskeletal lesions: Fifty percent have renal cysts, angiolipomas, and aneurysms; 30% to 50% have rhabdomyomas of the heart. Pulmonary lesions in 1% commonly lead to pneumothorax.
FIGURE 14-12. Tuberous sclerosis with renal angiomyolipomas. (A, B) Computed tomography (CT) images show characteristic fat density masses (arrows), the largest in the right kidney.
Neurofibromatosis is one of the most common inherited (autosomal dominant) disorders.
Clinical triad includes skin lesions, mental retardation, and skeletal deformities.
More than 99% of cases are in the category of neurofibromatosis Type 1 or Type 2.
Type 1 (two or more features)
Six or more café-au-lait skin lesions
Two or more neurofibromas or one plexiform neurofibroma
Inguinal or axillary freckling
Two or more iris hematomas
Parent, sibling, or child with Type 1
Type 2 (one feature)
Bilateral eighth nerve masses
Type 2 in parent, sibling, or child and an eighth nerve mass, or two of the following: neurofibroma, meningioma, glioma schwannoma, or posterior capsular lenticular capacity
Orbital and facial bone deformities
Spinal deformities (60%)
Spindle ribs and transverse processes
Bowing (especially tibia)
Pseudoarthrosis with pathologic fracture
Cranial nerve tumors
Peripheral nerve neurofibromas and schwannomas
Malignant degeneration of neural lesions 2% to 29%
Other associated lesions
FIGURE 14-14. Neurofibromatosis Type 1. Anteroposterior (AP) (A) and lateral (B) radiographs show tibial bowing with a healed midtibial fracture.
Ollier disease is a noninherited condition resulting in multiple asymmetrically distributed enchondromas.
Lesions lead to fractures in adults and children.
In adults, lesions may undergo malignant degeneration to chondrosarcoma (5% to 30%).
Multiple lytic expanding lesions are located predominantly in the extremities.
Flat bones of the pelvis may also be involved.
Lesions may contain calcification.
Maffucci syndrome is a rare disorder with multiple enchondromas and soft tissue hemangiomas.
The syndrome occurs in males and females, beginning in childhood.
Half of the cases are unilateral. The hand is most commonly involved.
Enchondromas may undergo malignant transformation to chondrosarcoma.
Multiple expanding lytic lesions that may contain calcifications
Soft tissue masses (hemangiomas) with phleboliths are characteristic.
Hereditary multiple exostosis is an autosomal dominant condition resulting in abnormal bone remodeling and bone deformities.
Patients present in childhood with palpable osseous masses, bone shortening, bowing, and joint deformities.
Osseous lesions relate to osteochondromas and are bilateral and near the physis.
Malignant degeneration (chondrosarcoma in 2% to 27%)
Most common in the knee and proximal humerus
Lesions are usually bilateral and symmetric.
Epiphyseal dysplasias have two broad categories:
Spondyloepiphyseal dysplasia: platyspondyly and beaking of the vertebra
Multiple epiphyseal dysplasia: minimal or no spine abnormalities
Multiple epiphyseal dysplasia may present in the tarda (childhood) or congenital (first year of life) forms.
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