Synovial Chondromatosis Synovial chondromatosis is a rare dysplasia seen in youngerpatients. It is associated with metaplastic cartilage within thesynovial lining of major joints such as the hip, knee, shoulder andelbow. It is twice as common in males as females and usuallyoccurs in patients in the 20-40 age group. It is a monarticulardisease that presents with symptoms of crepitation in the affectedjoint with mild, intermittent effusion sometimes associated withpain. Because of chronic irritation to the joint and damage to thearticular cartilage, osteoarthritis is an ultimate problem with thisdisease and can lead to a total joint replacement at a later age. Inrare instances this condition can mutate into a secondary chondro-sarcoma, usually around the hip or knee joint but seldom in theshoulder area. This usually occurs in the later years of life. In the early stages before the cartilage becomes calcified, thesynovial chondromatosis may be difficult to pick up on routineradiographic examination. As time passes, the cartilage begins
to calcify in a typical chondroid pattern that suggests the diagnosisof a chondroid tumor in or about a major joint. With excessiveproliferation, the cartilage can extrude out of the joint into adjacentsoft tissue, similar to what occurs with pigmented villonodularsynovitis. As the disease progresses, it is not unusual to seeenchondral ossification occurring within the cartilage when it isstill attached to the synovial lining and has access to a blood supply.Multiple loose bodies are common with this disease and can run ashigh as 200 pellets within a major joint that sometimes aggregrateinto a large mass that has the appearance of a chondrosarcoma. Treatment consists of a surgical resection of the loose bodies aswell as a subtotal synovectomy of the tissue that produces the loosebodies. Multiple surgical procedures may be required because of ahigh recurrence rate. As in PVNS, it is not unusual to see a solitaryfocus of synovial chondromatosis with the remaining synoviallining being normal in appearance with only a solitary mass ofcartilage attached to the synovial lining. This localized nodular form
is more common about the hip, knee and ankle area. It is verycommon to find loose bodies in a major arthritic joint in olderpatients secondary to osteoarthritis where the joint cartilage isbroken away from the joint surface and than becomes reattachedto the synovial lining and gives the pseudo-appearance of primarysynovial chondromatosis when, in fact, the primary etiology inthis so-called secondary form is degenerative osteoarthritis. Thesecondary form is seen in patients past the age of 50 years, where-as the primary dysplastic form arising from the synovial liningis seen during the first three to four decades of life.
CLASSIC Case #36433 year male with synovial chondromatoasis of shoulder
Myxoid Chondrosarcoma (Chordoid Sarcoma) The extra-skeletal myxoid chondrosarcoma is a very rare softtissue tumor in the deep muscle belly, occurring most often in theextremities in patients over 40 years of age. Males are affectedtwice as often as females. The tumor is slow growing and maycause local pain and tenderness. Common locations are the thigh,popliteal fossa, and shoulder girdle. It presents with the clinicalappearance of a myxoid liposarcoma. Pathologically, the tumorsare greyish to tannish brown, depending on the amount ofhemorrhage into the tumor. Because hemorrhage often occurs, itcan be mistaken for a hematoma. Histologically, the tumor has amyxoid appearance with chords and nests of anastomosing cellsthat have a chondroblastic appearance. The histology is verysimilar to that of chordoma of the sacrum. The tumor is consideredlow grade in most instances; it is slow growing but has the potential
for local recurrence and pulmonary metastases in about one-thirdof cases. Treatment consists of aggressive wide local resection oramputation, if needed, followed by local radiation therapy. Chemo-therapy is usually not indicated.
CLASSIC Case #383 Coronal T-1 MRI tumor 55 year male with myxoid chondrosarcoma distal thigh
Epithelioid Sarcoma The epithelioid sarcoma affects young adults and is mostcommonly seen in the fingers, hand and forearm where it isconsidered the most common soft tissue sarcoma next to thealveolar rhabdomysarcoma and synovial sarcoma. It can also occurin the popliteal area, the buttock, thigh, shoulder, foot and anklearea. It affects twice as many males as females. These tumors arefrequently misdiagnosed as a benign granulomatous process andare often attached to tendon sheaths and facial planes withassociated cutaneous ulcerations that may be multiple in nature.Calcification or even bone formation can occur in about 15% ofcases. The histological appearance of this lesion displays a distinctnodular growth pattern with epithelioid nests of cells at the centersurrounded by lymphocytic infiltration. The differential diagnosiswould include necrotizing infectious diseases such as tuberculosisor granuloma annulare or rheumatoid nodules. Regional lymph
node involvement occurs in about 35% of cases and metastases tothe lung in about 50% of cases. Because of the benign clinicalappearance of this lesion, it is common for surgeons to attemptlocal resection but there is a high recurrence rate that eventuallyleads to amputation. Local radiation therapy can help to decreasethe chance of local recurrence.
CLASSIC Case #38636 year male withepithelioid sarcomafoot ulceration
Extra-skeletal Ewing’s Sarcoma Ewing’s sarcoma is usually associated with primary tumor ofbone but in a small percentage of cases, Ewing’s sarcoma canoccur in soft tissue completely unattached to the skeletal system.However, the histological appearance and the clinical pictureassociated with soft tissue Ewing’s sarcoma is basically the sameas that of skeletal Ewing’s. This condition is seen in patientsbetween the age of 15 and 30 years. It occurs in males and femalesequally and is rare in black patients. The most common locationis the chest wall, followed by the lower extremities, paraspinousarea, pelvis, hip and retroperitoneum. The least common locationis the upper extremity. The reciprocal translocation of the longarm of chromosomes 11 and 22 is seen in soft tissue Ewing’s,just as it is in skeletal Ewing’s. The prognosis for five year survivalis approximately 65%, similar to that of skeletal Ewing’s. Treatmentconsists of wide local resection when possible, followed by
local radiation therapy if indicated. Adjuvant chemotherapy iscommonly used because of the excellent response, similar tothat of skeletal Ewing’s sarcoma.
CLASSIC Case #39028 year female withsoft tissue Ewing’ssarcoma anterior thighCoronal proton densityMRI
Clear Cell Sarcoma The clear cell sarcoma is thought to be a deep, non-cutaneousvariant of the pigmented melanoma. It is a very rare tumor affectingfemales more than males. It is typically seen between the ages of20 and 40 years. It usually occurs in tendon sheaths and fascialplanes, especially around the foot and ankle area, similar to theclinical appearance seen with synovial sarcoma with which it canbe confused. The tumor usually begins as a slow growing lump thathas a benign appearance but after a period of several years the tumorwill start growing more rapidly and become painful. It has a highpotential to metastasize to local lymph nodes and to the lung.Approximately 50% of patients with this tumor will be dead in fiveyears. The microscopic appearance is similar to that of the epithelioidsarcoma, especially if melanin is not found in the specimen.Treatment usually consists of wide local resection, if possible, but ahigh local recurrence rate is common because of its location in
extracompartmental structures such as tendon sheaths. If thatoccurs, amputation is carried out for local control of the disease.Local radiation therapy is utilized with attempts at wide resection.Adjuvant chemotherapy has been advised because of the poorprognosis but the response is usually not beneficial.
CLASSIC Case #393 35 year female with clear cell sarcoma hand
Myositis Ossificans Myositis ossificans is a heterotopic ossification within musclefascial planes seen typically in young athletic individuals in theiradolescence and early adult life. It occurs primarily in males andusually results from a significant injury to a muscle, such as atearing of the quadriceps muscle which is the most commonlocation for this problem. It is also seen in the gluteus maximusand the brachialis muscle at the elbow. The calcification is typicallynoted on x-ray three to four weeks after the injury. It tends to occurat the periphery of the damaged muscle and hematoma is usuallyseen in the central area. As the lesion matures the calcific rimaround the damaged muscle will appear as fairly mature boneand the central area will remain radiolucent, giving the so-calledzonal pattern that is almost diagnostic of traumatic myositisossificans. This is the opposite of osteosarcoma of soft tissue thathas the most dense portion of the calcifying lesion occurring centrallyand the more lytic portion at the periphery of the lesion. Myositis
ossificans can also be seen in older patients with no history oftrauma in which case the clinician becomes concerned about thepossibility of a neoplasm such as a synovial sarcoma or soft tissueosteosarcoma. Histologically, the lesion will have the appearanceof a healing fracture, including immature cartilage and boneformation, along with hematoma in the early stages. In rare cases,after a period of 25 or 30 years, these dormant lesions can reactivateand develop into an osteosarcoma. Treatment usually consists ofrest until the lesion matures after six months, at which point thepatient is usually asymptomatic. There is no reason to remove thelesion unless there is significant clinical disability related tostiffness of the adjacent joint. There is a hereditary congenital form of myositis ossificansreferred to as myositis ossificans progressiva, or the newer term-inology is fibrodysplasia ossificans progressiva, that is typicallyseen in children under the age of ten years. It presents with aclinical picture of progressive fibroblastic proliferation and
subsequent calcification and ossification of subcutaneous fat,muscles, tendons, appeneuroses, and ligaments. This condition canbe associated with symmetrical malformations of the digits withmicrodactyly of the thumbs and great toes, sometimes associatedwith a failure of segmentation of the digital bony structures. Thecondition usually presents between birth and the first six years ofage. It is inherited as an autosomal dominant trait. Males andfemales are equally affected and the calcification in soft tissues isusually precipitated by a local injury to the soft tissue. It occurstypically in the musculature of the back, shoulder, paravertebralregion and upper arms. Fusion of the tempromandibular joint canbe seen. If the respiratory muscles are affected, death can resultbecause of respiratory failure or pneumonia in early adult life. Theprognosis for survival is very poor and most patients die within thefirst ten to fifteen years of life. Biopsy or trauma of the affectedareas should be avoided because of new lesions that mightdevelop. There is no effective treatment or this condition.
CLASSIC Case #39512 year female withmyositis ossificansmedial thigh
fibrous tissueCut surgical specimen showing mature bone at periphery
Photomic showing reactive bone at periphery of lesion
Pigmented Villonodular Synovitis The etiology of pigmented villonodular synovitis (PVNS)remains controversial. It presents as an inflammatory synovialdisease, usually involving only one joint, but histologically thedisease presents with histiocytic proliferation in the subsynovialtissue that takes on the characteristics of a neoplastic conditionsimilar to that of a giant cell tumor. PVNS occurs typically in thesubsynovial tissue about major joints of the lower extremity inpatients between the ages of 20 and 40 years. The knee joint is themost common site, followed next by the hip, ankle and foot. It israre to see this disease in the upper extremity. The histiocyticproliferation in subsynovial tissues is similar to that seen in giantcell tumor of tendon sheathes in the hand and foot., The clinicalpicture in the knee joint is that of spontaneous swelling associatedwith pain and synovial hypertrophy. Hemarthrosis can result inmassive swelling about the knee joint and can occasionally result
in juxta-articular erosion of bone, similar to what is seen inrheumatoid synovitis. Other clinical conditions with a similarpresentation include hemophilia and coccydiomycosis. In fewerthan 10 % of cases this condition will present as a localized focalmass in the suprapatellar pouch of the knee or high in the poplitealspace posteriorly that can masquerade as a neoplastic conditionsuch as a synovial sarcoma. Treatment for the more generalized synovial involvement ofthe knee joint or other lower extremity joints consists of a subtotalsynovectomy that in many cases can be performed through anarthroscope. In more extensive cases an open procedure may benecessary. The recurrence rate is fairly high, in the range of 30%.In cases where multiple recurrences result, treatment with radiationtherapy in the neighborhood of 1500-3000 centigray by externalbeam is used. Injectable isotopes have also been used for radiationtreatment of recurrent cases. Secondary arthritic changes, especiallyin the knee joint, can occur as a late complication of this disease
and these changes could lead to a total joint replacement at theage of 50 or 60 years. On very rare occasion, this disease canconvert to a neoplastic sarcoma with a high degree of giant cellactivity. This is similar to the conversion of a giant cell tumor toa malignant sarcoma.