Enchondroma The enchondroma is one of the most common benign tumors seenin the skeletal system. It is centrally located and in 50% of the caseswill be found in small tubular bones of hands and feet where itarises as a hamartomatous process and frequently remains un-diagnosed throughout the life of the patient until which time asthey develop a pathologic fracture thru the lesion. The lesionshave a typical geographic pattern with sharp margination andfrequently demonstrate matrix calcification, especially as thepatient ages. In the hand or foot, the lesions frequently causemarked thinning of the surrounding cortex and dilatation of thebone, whereas with enchondromas found in larger bones, thereis minimal evidence of cortical invasion and little if any evidenceof cortical thinning or dilatation. It is rare for an enchondroma toconvert into a chondrosarcoma in the hand or foot, but in largerbones such as the femur or pelvis a primary enchondroma can
convert very gradually into a low grade chondrosarcoma. Theincidence of conversion is less than 5% of cases and almost alwaysin adults. In most cases, the enchondroma will be discovered as anincidental finding, because it is asymptomatic and non-disabling.There is no particular need to biopsy or bone graft the lesion unlessthe patient develops an interest in a specific sport or occupationalactivity that would put him at risk for fracture. If an acutefracture occurs, it is best to wait until the fracture heals and thenconsider the patient for a bone grafting procedure at a later date.
CLASSICCase #12038 year femaleenchondromadistal femur
Multiple Enchondromatosis (Ollier’s) Multiple enchondromatosis or Ollier’s disease, is a rare non-familial cartilagenous dysplasia that is typically seen on one halfof the body and appears similar to fibrous dysplasia. Extensivedisease of the metaphyseal areas of long bone can result in bowingand shortening. In the case of the femur a major bowing is seendistally compared to the proximal bowing seen in fibrous dysplasia.The cortical thinning and epiphyseal involvement seen in Ollier’sdisease is rarely seen in solitary enchondromas. The chance formalignant conversion to a low grade chondrosarcoma in adult lifeis about 25%.
CLASSIC Case #568 3 year male with multiple enchondromatosis
Multiple Enchondromatosis Plus Soft tissue Hemangiomatosis Maffucci’ Disease
Maffucci’s Syndrome Patients with multiple enchondromatosis or Ollier’s disease will onoccasion develop soft tissue hemangiomatosis in the same areasas the enchondromatosis is seen. This combination of both a bonycartilaginous and a soft tissue angiomatosis is known as Maffucci’ssyndrome. The clinical appearance of the multiple enchondromatosisis the same as Ollier’s disease but with a higher potential for amalignant conversion to a low grade chondrosarcoma in adult life.
CLASSICCase #58433 year maleMaffucci’s disease
Periosteal Chondroma The periosteal chondroma has the same basic pathology as theenchondroma except that it occurs on the surface of a tubularbone. It can occur as a hamartomatous process in growing patientsbut as with enchondroma it is usually asymptomatic and growthstops at bone maturity. The lesions are found in large bones, suchas the humerus and femur, and in the small bones of the hand andfoot. Radiographically one sees slight erosion into the adjacentcortex but the lesion will not penetrate into the medullary canal.There will be a sclerotic response at the base that extends aroundthe periphery of the lesion taking on the appearance of a blisteron the surface of the bone with matrix calcification seen mainlyat the periphery but found also in the central area. The lesionsusually stop growing before they reach the upper limit of 3-4 cmin diameter. If growth continues beyond this, one must stronglyconsider the possibility of a peripheral surface type chondrosarcoma
that would continue to grow after bone maturity. Periosteal sarcoma is a similar chondroid lesion found typicallyon large bones. It demonstrates a more aggressive pattern,permeation into surrounding cortical structures and a moreaggressive histology with some osteoid formation. Osteo-chondroma also has a similar appearance but would demonstratea more mature bony base on which a cap of cartilage is typicallyseen. In the case of the periosteal chondroma, the cartilageextends down into the depths of the tumor. Treatment consists of a simple resection without disturbingthe subadjacent cortex so that bone grafting or internal fixationdevices are not necessary. The recurrence rate is very low aftermaturity.
CLASSICCase #12117 year femaleperiosteal chondromadistal femur
Osteochondroma The solitaty osteochondroma or exostosis is one of the mostcommon benign bone tumors seen in the skeleton. As in theenchondroma, this condition is developmental, or hamartomatousin nature arising from the outer edge of the growth plate andgrowing down the metaphyseal side where it tends to point awayfrom the adjacent joint. Because it originates from the growth plate,it continues to grow during the growing years of the patient andthen stops at maturity. It is made up of a bony base with a pedunc-ulated stock with fatty marrow extending up inside the stock thathas a cartilagenous cap giving it the appearance of a cauliflower.Histologically, the cap has features of a normal growth plate if abiopsy is performed during the growing years. Most of these lesionsarise from large bones, especially about the knee joint, proximalfemur, and proximal humerus. In the proximal humerus, theosteochondroma is usually sessile-based without a typical pedunc-
ulated stock and is frequently misdiagnosed for that reason.Multiple hereditary exostosis presents with multiple lesions through-out the skeletal system and is considered to be an autosomaldominant disorder, being one-tenth as common as the solitaryosteochondroma which is not inherited. The conversion of a solitary osteochondoma to a chondro-sarcoma can only occur in the adult. It is an extremely rare eventcompared to the 1% chance of a malignant conversion in multiplehereditary exostosis. It is the cartilaginous cap that converts into alow grade secondary type of peripheral chondrosarcoma with anexcellent prognosis for survival compared to a central chondro-sarcoma. These malignant conversions usually arise from largeosteochondromas seen in more proximal locations, such as aroundthe hip or pelvis. Because osteochondromata are usually withoutsymptoms, surgical treatment is frequently unnecessary unless thelesions create mechanical problems such as around the knee joint
where larger lesions can interfere with normal ambulation.Sometimes, a large proximal lesion with a cartilage cap exceeding2 cm should be prophylactically resected in order to avoid apossible chondrosarcoma. When removing an osteochondroma, itis necessary only to remove the complete cartilaginous cap,leaving most of the bony base intact to avoid a facture.
CLASSICCase #12225 year maleosteochondromatibia
Chondroblastoma The chondroblastoma is a benign, cartilage forming tumor seenin the metaepiphyseal area of bone in children and young adults.The histologic appearance is typical of a giant cell tumor in youngadults. The chondroblastoma is one fifth as common as the giantcell tumor and the majority of cases will occur during the seconddecade of life. It is rare to find the giant cell tumor in patientsunder the age of 13 years. The most common location for thechondroblastoma is in the epiphysis of the distal femur, proximaltibia, and proximal humerus. These lesions are usually locatednear a joint and are quite painful because of a secondary inflamm-atory synovitis of the adjacent joint that can masquerade as apyarthrosis. It is not unusual to find an aneurysmal bone cystassociated with the chondroblastoma, similar to the situation seenwith giant cell tumors. Histologically, one sees round polyhedral-shaped stromal cells located in clear cytoplasmic halos that gives
the appearance of chicken wire under the microscope. Giant cellsare frequently associated with the chondroid tissue that gives theappearance of a giant cell tumor. It is very rare for a chondro-blastoma to convert to a malignant tumor, however, as in the caseof giant cell tumor, they can metastasize to the lung and stillcarry an excellent prognosis for survival. Treatment consists of a simple curettement of the lesionfollowed by packing the defect with either bone graft or bonecement. There is a relatively low (10%) recurrence rate.
CLASSIC Case #123 12 year female with chondroblastoma proximal tibia
Chondromyxoid Fibroma Chondromyxoid fibroma is a very rare solitary benign tumor seenin bone. It occurs typically in the second or third decade of life andaffects men more than women. By far the more common locationfor this lesion is in the proximal tibial metaphysis, followedsecond by the distal femur and the first ray of the foot. This lesionis slow growing and is associated with mild symptoms of pain.Radiographically, there is a lytic lesion of bone with a soap-bubbly appearance secondary to the thin sclerotic peripheralmargin giving it a pseudoloculated appearance similar to that ofa solitary bone cyst. The adjacent cortex is frequently thinned outand slightly dilated, similar to the pattern that is seen in fibrousdysplasia. Histologically, there will be evidence of benign fibroustissue with large areas of myxomatous degeneration with reactivemacrophage activity seen at the periphery of the lesion that couldsuggest the diagnosis of a chondrosarcoma.
Treatment for this lesion consists of a simple curettement and bonegrafting. The fairly high recurrence rate of 25% can be reduced bya more aggressive, marginal resection of the tumor. Occasionally,this lesion can convert into a chondrosarcoma.
CLASSICCase #12411 year malechondromyxoid fibromaproximal tibia