Miscellaneous Conditions

Jeffrey J. Peterson

Thomas H. Berquist

▪ BONE ISLANDS (ENOSTOSIS)

KEY FACTS

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.
Radiographic features:
- 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.

FIGURE 14-1. Bone island in the proximal tibia. Axial (A) and coronal (B) reformatted computed tomography (CT) images demonstrate a sclerotic focus with speculated margins in the proximal tibia. Coronal T1-weighted (C) magnetic resonance (MR) image shows the lesion to be longitudinally oriented. Bone scan (D) demonstrates no abnormal scintigraphic activity to correspond to the lesion.

FIGURE 14-1. (continued)

SUGGESTED READING

Greenspan A, Steiner G, Knutzon R. Bone island (enostosis): clinical significance and radiologic and pathologic correlations. Skeletal Radiol. 1991;20(2):85-90.

Hall FE, Goldberg RP, Davies JAK, et al. Scintigraphic assessment of bone islands. Radiology. 1980;135:737-742.

▪ OSTEOPOIKILOSIS

KEY FACTS

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.
Radiographic features:
- 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.

FIGURE 14-2. Osteopoikilosis. Anteroposterior (AP) radiograph of the pelvis and hips shows multiple small sclerotic foci in the proximal femora, ischia, and acetabuli.

SUGGESTED READING

Ellanti P, Clarke B, Gray J. Osteopoikilosis. Ir J Med Sci. 2010;179(4):615-616.

Green AE, Ellowood WH, Collins JR. Melorheostosis and osteopoikilosis. Am J Roentgenol. 1962;87:1096-1117.

▪ OSTEOPATHIA STRIATA

KEY FACTS

Osteopathia striata is a rare autosomal dominant inherited condition related to osteopoikilosis.
Patients are usually asymptomatic.
Radiographic features:
- 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.

FIGURE 14-3. Osteopathia striata. Anteroposterior (AP) radiograph of the knees shows linear striations in the distal femora and proximal tibia bilaterally.

SUGGESTED READING

Bass HN, Weiner JR, Goldman A, et al. Osteopathia striata syndrome. Clinical, genetic and radiologic considerations. Clin Pediatr (Phila). 1980;19(5):369-373.

Hurt RL. Osteopathia striata—Voorhoeve disease. J Bone Joint Surg. 1953;35B:89-96.

▪ MELORHEOSTOSIS

KEY FACTS

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.
Radiographic features:
- 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
  - Scleroderma
  - Neurofibromatosis
  - Osteopoikilosis
  - Osteopathia striata
  - Hemangiomas

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.

FIGURE 14-5. Melorheostosis. Standing view of the knees shows sclerosis and cortical thickening that crosses the joint into the soft tissues. The tibia is also involved.

SUGGESTED READING

Bansal A. The dripping candle wax sign. Radiology. 2008;246(2):638-640.

Morris JM, Samilson RL, Corey CL. Melorheostosis. J Bone Joint Surg. 1963;45A:1191-1206.

▪ PROGRESSIVE DIAPHYSEAL DYSPLASIA (ENGELMANN DISEASE)

KEY FACTS

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.
Radiographic features:
- Symmetric distribution
- Diaphyseal cortical thickening involving endosteal and periosteal surfaces
- Normal epiphysis and metaphysis
- Relative elongation of involved extremities
- Muscle atrophy
Differential diagnosis: chronic infection, infantile cortical hyperostosis, fibrous dysplasia

FIGURE 14-6. Engelmann disease. (A) Radionuclide bone scan shows symmetric increased cortical uptake in the femora, tibiae, and upper extremities. Anteroposterior (AP) radiographs of the femur (B) and tibia (C) show marked diaphyseal cortical thickening with sparing of the metaphyses and epiphyses.

SUGGESTED READING

Kumar B, Murphy WA, Whyte MP. Progressive diaphyseal dysplasia (Engelmann disease): scintigraphic-radiographic-clinical correlations. Radiology. 1981;140:87-92.

▪ CLEIDOCRANIAL DYSPLASIA (CLEIDOCRANIAL DYSOSTOSIS)

KEY FACTS

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.
Radiographic features:
- 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

FIGURE 14-7. Cleidocranial dysplasia. (A) Anteroposterior (AP) view of the skull shows multiple wormian bones along the suture lines. (B) AP view of the upper chest shows an absent right clavicle and small hypoplastic medial segment (arrow) on the left.

SUGGESTED READING

Jarvis JL, Keats TE. Cleidocranial dysostosis. A review of 40 new cases. Am J Roentgenol. 1974;121:5-16.

▪ OSTEOPETROSIS

KEY FACTS

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.
Radiographic features:
- 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.

FIGURE 14-9. Osteopetrosis tarda. Lateral (A) and anteroposterior (AP) (B) radiographs of the lumbar spine show a bone-within-a-bone appearance.

SUGGESTED READING

Shapiro F, Glimcher MJ, Holtrop ME, et al. Human osteopetrosis. J Bone Joint Surg. 1980;62A:384-399.

Stark Z, Savarirayan R. Osteopetrosis. Orphanet J Rare Dis. 2009;4:5.

▪ MASTOCYTOSIS

KEY FACTS

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.

FIGURE 14-10. Mastocytosis. (A) Anteroposterior (AP) radiograph of the lumbar spine and pelvis shows generalized bone sclerosis and cortical thickening. There are more focal foci of sclerosis in the femoral heads. AP (B) and lateral (C) radiographs of the lumbar spine and pelvis in a different patient show diffuse small sclerotic foci.

SUGGESTED READING

McKenna MJ, Frame B. The mast cell and bone. Clin Orthop. 1985;200:226-233.

Nguyen BD. CT and scintigraphy of aggressive lymphadenopathic mastocytosis. Am J Roentgenol. 2002;178(3):769-770.

▪ TUBEROUS SCLEROSIS

KEY FACTS

Tuberous sclerosis is an autosomal dominant inherited disorder.
Characteristic features include seizure disorders, mental retardation, and cutaneous hamartomas.
Radiographic features:
- 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 14-11. Tuberous sclerosis. Anteroposterior (AP) radiograph of the pelvis shows oval- or flame-shaped areas of sclerosis in both iliac wings. There is an impacted left femoral neck fracture with pin fixation unrelated to the bone changes of tuberous sclerosis.

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.

FIGURE 14-12. (continued)

FIGURE 14-13. Tuberous sclerosis. Axial T2-weighted magnetic resonance (MR) image shows multiple areas of signal abnormality (arrows) resulting from cortical tubers.

SUGGESTED READING

Medley BE, McLeod RA, Houser OW. Tuberous sclerosis. Semin Roentgenol. 1976;11:35-54.

Wood B, Leiberman E, Larding B, et al. Tuberous sclerosis. Am J Roentgenol. 1992;158:750.

▪ NEUROFIBROMATOSIS

KEY FACTS

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

Optic glioma

Two or more iris hematomas

Osseous lesion

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

Radiographic features:
- Osseous features
- Orbital and facial bone deformities
- Spinal deformities (60%)
- Scoliosis
- Kyphoscoliosis
- Vertebral scalloping
- Pedicle erosion
- Spindle ribs and transverse processes
- Extremities
- Bowing (especially tibia)
- Pathologic fracture
- Hypoplastic fibula
- Pseudoarthrosis with pathologic fracture
Neural
- Meningoceles
- Cranial nerve tumors
- Peripheral nerve neurofibromas and schwannomas
- Malignant degeneration of neural lesions 2% to 29%
Other associated lesions
- Neuroblastoma
- Pheochromocytoma
- Thyroid carcinoma
- Wilms tumor
- Rhabdomyosarcoma
- Leukemia

FIGURE 14-14. Neurofibromatosis Type 1. Anteroposterior (AP) (A) and lateral (B) radiographs show tibial bowing with a healed midtibial fracture.

FIGURE 14-15. Neurofibromatosis Type 1. Oblique cervical spine radiographs (A, B) depict diffuse widening of the neural foramina at all levels. Axial computed tomography (CT) (C) image shows bilateral neurofibromas within the neural foramina and elsewhere through the neck. Axial T2-weighted (D) shows the numerous hyperintense neurofibromas to better advantage.

FIGURE 14-16. Neurofibromatosis Type 2. Bilateral vestibular nerve schwannomas and multiple meningiomas. (A) Postcontrast axial magnetic resonance (MR) image shows bilateral large vestibular nerve schwannomas extending into the internal auditory canals and compressing the pons. Sagittal (B) and coronal enhanced (C) T1-weighted images show multiple meningiomas (arrows).

SUGGESTED READING

Aoki S, Barkovich AJ, Nishimura K, et al. Neurofibromatosis types 1 and 2: cranial MR findings. Radiology. 1989;172(2):527-534.

Fortman BJ, Kuszyk BS, Urban BA, et al. Neurofibromatosis type 1: a diagnostic mimicker at CT. Radiographics. 21(3):601-612.

Sevick RJ, Barkovich AJ, Edwards MS, et al. Evolution of white matter lesions in neurofibromatosis type 1: MR findings. Am J Roentgenol. 1992;159:171-175.

▪ OLLIER DISEASE (ENCHONDROMATOSIS)

KEY FACTS

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%).
Radiographic features:
- Multiple lytic expanding lesions are located predominantly in the extremities.
- Flat bones of the pelvis may also be involved.
- Lesions may contain calcification.

FIGURE 14-17. Ollier disease. (A) Posteroanterior (PA) chest radiograph shows multiple expanded calcified rib lesion (arrows). (B) PA view of the hand shows enchondromas in the second to fourth rays. Anteroposterior (AP) radiographs of the pelvis (C) and femora (D) show multiple enchondromas in the left femur. The largest expand the distal femur.

SUGGESTED READING

Milgram JW. The origins of osteochondromas and enchondromas. A histopathologic study. Clin Orthop. 1983;174:264-284.

▪ MAFFUCCI SYNDROME

KEY FACTS

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.
Radiographic features:
- Multiple expanding lytic lesions that may contain calcifications
- Soft tissue masses (hemangiomas) with phleboliths are characteristic.

FIGURE 14-18. Maffucci syndrome. Oblique radiograph shows multiple enchondromas and soft tissue masses with vascular calcifications.

SUGGESTED READING

Strang C, Ronnie I. Dyschondroplasia and hemangiomata (Maffucci’s syndrome). J Bone Joint Surg. 1950;32B:376-383.

Zwenneke Flach H, Ginai AZ, Wolter Oosterhuis J. Best cases from the AFIP. Maffucci syndrome: radiologic and pathologic findings. Armed Forces Institutes of Pathology. Radiographics. 2001;21(5):1311-1316.

▪ HEREDITARY MULTIPLE EXOSTOSIS

KEY FACTS

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.
Complications:
- Pathologic fracture
- Neurovascular injury
- Bursa formation
- Malignant degeneration (chondrosarcoma in 2% to 27%)
Radiographic features:
- Osteochondroma-like lesions
- Most common in the knee and proximal humerus
- Lesions are usually bilateral and symmetric.

FIGURE 14-19. Hereditary multiple exostosis. Radiographs of the humeri (A, B), left hand and wrist (C), both ankles (D), and feet (E) demonstrate multiple exostoses with bone and joint deformities most obvious in the hand and wrist.

SUGGESTED READING

Murphey MD, Choi JJ, Kransdorf MJ, et al. Imaging of osteochondroma: variants and complications with radiologic-pathologic correlation. Radiographics. 2000;20(5):1407-1434.

Wilner D. Radiology of Bone Tumors and Allied Disorders. Philadelphia: WB Saunders; 1982.

▪ EPIPHYSEAL DYSPLASIAS

KEY FACTS