Bone Tumors
Enchondroma
<<James C. Wittig, MD
Sarcoma Surgeon
Orthopedic Oncologist
GENERAL INFORMATION
Enchondroma is a benign indolent intramedullary hyaline cartilage neoplasm
Accounts for 10% of all benign osseous tumors
Limited growth, most lesions are less than 5 cm in maximal dimension
Bones grow from a cartilaginous growth plate that gradually lengthens and turns into bone as it lengthens. An enchondroma can be thought of as an island of cartilage within the bone that never transformed into normal bone. Enchondromas usually reside within the medullary canal of the bone and do not grow. In selected bones such as those of the digits of the hand or feet it may weaken the bone and predispose it to fracture.
Enchondroma
Types:
Solitary Enchondroma
Multiple Enchondromas (Enchondromatosis/Ollier’s Disease)
Maffucci Syndrome (Multiple Enchondromas and Soft Tissue Hemangiomas)
CLINICAL PRESENTATION
Signs/Symptoms: Depends on location
Most long bone enchondromas are asymptomatic and found incidentally
Phalangeal tumors may be painful due to stress fractures
Prevalence:
No clear sex predilection
Age:
Range: Wide distribution; 5 – 70 years
60% of enchondromas are discovered in patients between 15 to 40 years of age
Sites: 50% involve hands and feet (mostly phalanges)
Proximal Humerus, Femur most common long bones
Enchondromas of the pelvis, vertebrae and ribs are uncommon
Almost all hyaline cartilage tumors of the pelvis are considered malignant based on anatomic location no matter what the pathology shows. These tumors will ultimately grow locally and have the potential to dedifferentiate or change into a higher grade chondrosarcoma.
RADIOGRAPHIC PRESENTATION
Localized, radiolucent defect usually with punctate calcifications
Calcifications are typical but not always present
Matrix may demonstrate various degrees of calcification
Calcifications are stippled, punctate, popcorn like calcifications and "Ring and Arc" calcifications
Cartilage tumors grow in a lobular manner. The perimeters of the lobules undergo
enchondral ossification that may calcify. If the entire perimeter of the lobule calcifies it appears
radiographically as a "Ring". If a portion of the perimeter of a lobule calcifies it forms an "Arc" on
an X-ray.
May be located centrally or eccentrically
Grows eccentrically or concentrically (phalanges)
Cortex may be scalloped and thinned in the phalanges
MRI is better to see noncalcified chondroid lesions and the full extent of lesions
Most commonly found in metaphysis
Plain X-Ray:
Geographic lytic lesion
Central often metaphyseal in long bones
Can be eccentric also
Expansile remodeling with thinned cortex
Chondroid matrix with calcifications in majority of tumors
Approximately 20% have limited or no calcifications
MRI
Lobulated margin
Marked increased intensity long TR images
Calcified chondroid – low intensity all sequences
MRI:
Lobulated margin (Lobular Growth Pattern)
T1 Weighted Images: Intermediate Signal Intensity
Calcifications will be low signal
T2 Weighted Images: High Signal Intensity
High water content shows as high signal on T2 weighted images
Calcifications will be low signal
Marked increased intensity long TR images
Calcified chondroid – low intensity all sequences
There should never be any cortical destruction nor a soft tissue component. If this exists then the tumor must be a chondrosarcoma.
Endosteal scalloping and cortical expansion is acceptable for phalangeal tumors. In most benign long bone cartilage tumors there is minimal endosteal scalloping but there should be no cortical expansion nor thickening. There should be no cortical destruction and no soft tissue component associated with an enchondroma. Cortical destruction, periosteal thickening, cortical expansion and a soft tissue component indicates a chondrosarcoma of the long bone.
CT Scan:
Best for demonstrating subtle calcifications not visible on plain X-rays
Useful for demonstrating "Ring and Arc" calcification pattern which helps differentiate from a bone infarct
Cortical erosion and scalloping is best demonstrated with a CT scan |
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Plain X-Ray: Enchondroma of Proximal Phalanx
Geographic lesion
Stippled calcifications in lesion
Phalanx is expanded
Significant endosteal scalloping
No cortical destruction
No soft tissue extension
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Cortex Scalloped and Expanded
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X-Ray and MRI of Enchondroma of Middle Phalanx
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Geographic Lesion
Bony Expansion
Minimal Calcification
Some Enchondromas
do not calcify |
T1: Intermediate Signal
Lobular Growth
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T2: High Signal
No Soft Tissue Component |
CT Scan: Enchondroma of Middle Phalanx
There was no mineralization detected in this enchondroma
Bone Scan: Enchondroma of Middle Phalanx
Enchondromas demonstrate increased uptake on a bone scan
Most benign cartilage tumors demonstrate uptake that is less than the normal uptake in the ASIS although some may have higher uptake than ASIS |
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Bone Scan: Enchondroma of Middle Phalanx
Uptake in Lesion is Less than Anterior Superior Iliac Spine (ASIS)
Plain X-Ray: Enchondroma of Proximal Humerus
Metaphyseal Tumor
Heavy Calcifications
Ring and Arc Pattern of Calcifications
Minimal Endosteal Scalloping
No Cortical Destruction
No Periosteal Reaction
No Soft Tissue Component
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Plain X-Ray: Enchondroma of Proximal Humerus
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Metaphyseal Tumor
Heavy Calcifications
Ring and Arc Pattern of Calcifications
Minimal Endosteal Scalloping
No Cortical Destruction
No Periosteal Reaction
No Cortical Destruction
No Soft Tissue Component
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Plain X-Ray: Enchondroma of Femur
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Ring and Arc Calcification
No Endosteal Scalloping |
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CT Scan: Enchondroma of Femur
Minimal Endosteal Scalloping is Acceptable
CT Scan: Enchondroma of Femur: Ring and Arc-Calcifications
Small Rings/Circles of Calcification
No Endosteal Erosion/Scalloping
Cortex is Intact
X-Ray and CT Scan: Enchondroma of Femur
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Ring and Arc Calcifications
Minimal Endosteal Scalloping
Cortex Intact
No Soft Tissue Component
No Periosteal Reaction
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PATHOLOGY
Rests of hyaline cartilage with a lobular growth pattern
Cells are within lacunae
Hypocellular with cells spaced apart separated by matrix
Cells have small nuclei and are similar size and shape (no pleomorphism)
No mitotic figures
The matrix has a ground glass basophilic appearance
The matrix contains glycosaminoglycans that attract fluid/water and gives it a bsophilic appearance and show as high signal intensity on T2 weighted MRI
The collagen of the matrix is organized in a manner such that the refractile index under a microscope gives a ground glass appearance to the matrix. One can not visualize the actual collagen fibers.
Hyaline cartilage often with myxoid areas
Variable amorphous calcification and enchondral ossification
May cause mild expansile remodeling of bone and cortical thinning
GROSS PATHOLOGY
Fragments of enchondroma after curettage are bluish white and glistening hyaline cartilage
There may be yellow calcified foci
Cartilage grows in a lobular manner and hence in a completely resected specimen there will be local lobules of mature cartilage
MICROSCOPIC PATHOLOGY
Enchondromas are well defined lesions with cartilage arranged in lobules that are separated by fibrovascular septa
Enchondral ossification may occur around periphery of lobules and when calcified appear as "Rings and Arcs" on X-rays
Cells are in lacunae and have small dark nuclei
Low cell count, cells appear bland with few chondrocytes and are similar size and shape
Although some enchondromas may have areas that are hypercellular and may have two or three cells within a lacunae
No entrapment or destruction of trabeculae
There should be no myxoid change in long bone lesions (there is occasional myxoid change in enchondromas of the digits)
Presence of myxoid change is sign of malignancy
Enchondromas of digits can have hypercellularity, bi and trinucleated cells and myxoid change and still be considered benign
Microscopic Pathology: Enchondroma
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Cells in Lacunai
Hypocellular
Lobular Growth
No Pelomorphiam
Matrix Ground Glass
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Enchondral Ossification around
Periphery
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Microscopic Pathology: Enchondroma
Microscopic Pathology: Enchondroma
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Hypocellular
Cells are Bland and in Lacunae
Occasional Binucleated Cells
No Mitoses
Binucleated Lacunae (arrow) |
Microscopic Pathology: Enchondroma
Microscopic Pathology: Enchondroma of a Digit
Slightly More Hypercellular
Occasional Binucleated Cells
No Mitoses
Minimal Pleomorphism |
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Microscopic Pathology: Enchondroma of a Digit
Occasional Areas of Myxoid Change are Acceptable
Cells in Lacunae (arrow left)
Myxoid Matrix (arrow right)
DIFFERENTIAL DIAGNOSIS
The main differential is with a low grade (Grade 1) chondrosarcoma
Can be very difficult to differentiate from a Grade 1 Chondrosarcoma from an enchondroma based on histology
It is easy to differentiate from a grade 2 or 3 chondrosarcoma by means of histology which are hypercellular, pleomorphic and demonstrate mitotic figures
Radiographs and clinical history are important for differentiation
Biopsies are not useful for differentiating an enchondroma from a low grade chondrosarcoma
Features consistent with chondrosarcoma
Pain attributable to lesion
Age greater than 50
Cortical destruction and a soft tissue mass
Periosteal reaction and thickening
Endosteal erosion>2/3 cortical thickness on a CT scan
Size greater than 5 cm
Bone Scan: Lesion that is hotter than ASIS
TREATMENT
Enchondromas are benign, indolent (not growing) tumors
Indications for surgery:
Digits: Impending or actual pathological fracture
Intralesional curettage and bone graft or cement
Long bones: Rare to fracture—usually observe
If grows it is considered chondrosarcoma and would recommend surgery accordingly
PROGNOSIS
Recurrence rate following curettage is <5%
Recurrence of an enchondroma suggests malignancy
There are rare cases where enchondromas can dedifferentiate into a chondrosarcoma or dedifferentiated chondrosarcoma (low grade chondrosarcoma with an osteosarcoma, fibrosarcoma or malignant fibrous histiocytoma arising adjacent to it)
Enchondromatosis
(Multiple Enchondromas/Ollier Disease
Enchondromatosis is a rare disorder that is not hereditary in which the patient is afflicted with multiple intraosseous cartilaginous tumors or enchondromas.
Clinical Data:
Mild male predilection
Present in childhood
Usually affects the extremities
Variable severity
May be predominantly unilateral or affect a single extremity/limb
Affected limb is often shortened and deformed and angulated
May become stable at puberty
Higher risk of malignant transformation to chondrosarcoma (5-50%) as opposed to an isolated enchondroma
Marked skeletal deformity
Not hereditary
Enchondromas in enchondromatosis may involve the metaphysis, diaphysis, epiphysis and articular cartilage
Microscopic Pathology
Hypercellular with large number of binucleated chondrocytes
Higher degree of cellularity and atypia compared to isolated enchondroma
Diagnosis of benign cartilage from a chondrosarcoma in setting of enchondromatosis is very difficult. Necrosis, myxoid change and radiographic studies demonstrating cortical destruction or a soft tissue mass are consistent with a chondrosarcoma
Chondrosarcoma arising in enchondromatosis
Patients with enchondromatosis are predisposed to developing chondrosarcomas and reports have documented up to a 50% risk for developing a chondrosarcoma over a lifetime.
Usually there is pain, cortical destruction and an enlarging mass
Most are low grade chondrosarcomas but dedifferentiated chondrosarcomas can also occur
Most patients are between the ages of 30-60 when they develop a secondary chondrosarcoma
The most common sites to undergo malignant change are the scapula, rib cage and pelvis
Enchondromatosis
Enchondromatosis
Enchondromatosis
Chondrosarcoma arising in enchondromatosis -
The prognosis for patients who develop a chondrosarcoma in setting of enchondromatosis is the same as a patient who develops a chondrosarcoma without a pre-existing condition. Low grade chondrosarcomas are associated with a good prognosis and mot patients are cured with surgical removal. Patients who develop a dedifferentiated chondrosarcoma have a high risk of developing metastases, dismal prognosis and high mortality rate.
Maffucci Syndrome
(Described in 1881 by Maffucci as enchondromatosis with hemangiomas)
Clinical Data:
Very rare; Nonhereditary
Multiple Enchondromas
Cavernous Hemangiomas anywhere in skin and subcutaneous tissues of body
May be unilateral or bilateral, may be only a few or many
Phleboliths (calcifications) usually seen in hemangiomas on X-ray
Mild male predilection
Hands and feet greatest involvement
Complications of hemangiomas
Malignant Transformation: Chondrosarcoma (15-20%) Vascular Sarcoma (3-5%) Ovarian Malignancy Glioma and Carcinoma Unrelated to bone or soft tissue
Imaging characteristics:
Lesions seen in infancy
Typical enchondromas
Geographic IA-IIB with expansion
Lytic columns from epiphyseal plate
Chondroid matrix calcification
Growth disturbance and bowing
Enchondroma growth slows after growth plate closure
Maffucci: Soft tissue mass/hemangiomas with phleboliths
Chondrosarcomatous transformation
New bone destruction
New periosteal reaction
Disorganized or destroyed matrix calcification
Plain X-Ray of Hand: Maffucci Syndrome
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Enchondromas
Phleboliths
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Plain X-Ray of Hand: Maffucci Syndrome
Plain X-ray: Enchondromatosis of Pelvis
Maffucci’s Syndrome
Plain X-rays: Enchondromatosis
Maffucci's Syndrome
Example of Chondrosarcoma of Metacarpal of Hand
There is cortical destruction and a soft tissue mass
Enchondromas do not extend into the soft tissues
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