The document describes several cases of rare soft tissue tumors, including:
1) Four cases of epithelioid sarcoma affecting the foot, forearm, and wrist in patients aged 22-36, which present as ulcerated lesions and are difficult to diagnose.
2) Three cases of myxoid chondrosarcoma in the thigh, shoulder, and leg in patients aged 41-65, which appear similar to hematomas and have a characteristic myxoid and chordoid pathology.
3) Several cases of synovial chondromatosis, juxta-articular chondroma, and secondary synovial chondromatosis affecting various large joints in patients aged 13
4. Synovial Chondromatosis
Synovial chondromatosis is a rare dysplasia seen in younger
patients. It is associated with metaplastic cartilage within the
synovial lining of major joints such as the hip, knee, shoulder and
elbow. It is twice as common in males as females and usually
occurs in patients in the 20-40 age group. It is a monarticular
disease that presents with symptoms of crepitation in the affected
joint with mild, intermittent effusion sometimes associated with
pain. Because of chronic irritation to the joint and damage to the
articular cartilage, osteoarthritis is an ultimate problem with this
disease and can lead to a total joint replacement at a later age. In
rare instances this condition can mutate into a secondary chondro-
sarcoma, usually around the hip or knee joint but seldom in the
shoulder area. This usually occurs in the later years of life.
In the early stages before the cartilage becomes calcified, the
synovial chondromatosis may be difficult to pick up on routine
radiographic examination. As time passes, the cartilage begins
5. to calcify in a typical chondroid pattern that suggests the diagnosis
of a chondroid tumor in or about a major joint. With excessive
proliferation, the cartilage can extrude out of the joint into adjacent
soft tissue, similar to what occurs with pigmented villonodular
synovitis. As the disease progresses, it is not unusual to see
enchondral ossification occurring within the cartilage when it is
still attached to the synovial lining and has access to a blood supply.
Multiple loose bodies are common with this disease and can run as
high as 200 pellets within a major joint that sometimes aggregrate
into a large mass that has the appearance of a chondrosarcoma.
Treatment consists of a surgical resection of the loose bodies as
well as a subtotal synovectomy of the tissue that produces the loose
bodies. Multiple surgical procedures may be required because of a
high recurrence rate. As in PVNS, it is not unusual to see a solitary
focus of synovial chondromatosis with the remaining synovial
lining being normal in appearance with only a solitary mass of
cartilage attached to the synovial lining. This localized nodular form
6. is more common about the hip, knee and ankle area. It is very
common to find loose bodies in a major arthritic joint in older
patients secondary to osteoarthritis where the joint cartilage is
broken away from the joint surface and than becomes reattached
to the synovial lining and gives the pseudo-appearance of primary
synovial chondromatosis when, in fact, the primary etiology in
this so-called secondary form is degenerative osteoarthritis. The
secondary form is seen in patients past the age of 50 years, where-
as the primary dysplastic form arising from the synovial lining
is seen during the first three to four decades of life.
133. Myxoid Chondrosarcoma
(Chordoid Sarcoma)
The extra-skeletal myxoid chondrosarcoma is a very rare soft
tissue tumor in the deep muscle belly, occurring most often in the
extremities in patients over 40 years of age. Males are affected
twice as often as females. The tumor is slow growing and may
cause local pain and tenderness. Common locations are the thigh,
popliteal fossa, and shoulder girdle. It presents with the clinical
appearance of a myxoid liposarcoma. Pathologically, the tumors
are greyish to tannish brown, depending on the amount of
hemorrhage into the tumor. Because hemorrhage often occurs, it
can be mistaken for a hematoma. Histologically, the tumor has a
myxoid appearance with chords and nests of anastomosing cells
that have a chondroblastic appearance. The histology is very
similar to that of chordoma of the sacrum. The tumor is considered
low grade in most instances; it is slow growing but has the potential
134. for local recurrence and pulmonary metastases in about one-third
of cases. Treatment consists of aggressive wide local resection or
amputation, if needed, followed by local radiation therapy. Chemo-
therapy is usually not indicated.
135. CLASSIC Case #383 Coronal T-1 MRI
tumor
55 year male with myxoid chondrosarcoma distal thigh
149. Epithelioid Sarcoma
The epithelioid sarcoma affects young adults and is most
commonly seen in the fingers, hand and forearm where it is
considered the most common soft tissue sarcoma next to the
alveolar rhabdomysarcoma and synovial sarcoma. It can also occur
in the popliteal area, the buttock, thigh, shoulder, foot and ankle
area. It affects twice as many males as females. These tumors are
frequently misdiagnosed as a benign granulomatous process and
are often attached to tendon sheaths and facial planes with
associated cutaneous ulcerations that may be multiple in nature.
Calcification or even bone formation can occur in about 15% of
cases. The histological appearance of this lesion displays a distinct
nodular growth pattern with epithelioid nests of cells at the center
surrounded by lymphocytic infiltration. The differential diagnosis
would include necrotizing infectious diseases such as tuberculosis
or granuloma annulare or rheumatoid nodules. Regional lymph
150. node involvement occurs in about 35% of cases and metastases to
the lung in about 50% of cases. Because of the benign clinical
appearance of this lesion, it is common for surgeons to attempt
local resection but there is a high recurrence rate that eventually
leads to amputation. Local radiation therapy can help to decrease
the chance of local recurrence.
173. Extra-skeletal Ewingâs Sarcoma
Ewingâs sarcoma is usually associated with primary tumor of
bone but in a small percentage of cases, Ewingâs sarcoma can
occur in soft tissue completely unattached to the skeletal system.
However, the histological appearance and the clinical picture
associated with soft tissue Ewingâs sarcoma is basically the same
as that of skeletal Ewingâs. This condition is seen in patients
between the age of 15 and 30 years. It occurs in males and females
equally and is rare in black patients. The most common location
is the chest wall, followed by the lower extremities, paraspinous
area, pelvis, hip and retroperitoneum. The least common location
is the upper extremity. The reciprocal translocation of the long
arm of chromosomes 11 and 22 is seen in soft tissue Ewingâs,
just as it is in skeletal Ewingâs. The prognosis for five year survival
is approximately 65%, similar to that of skeletal Ewingâs. Treatment
consists of wide local resection when possible, followed by
174. local radiation therapy if indicated. Adjuvant chemotherapy is
commonly used because of the excellent response, similar to
that of skeletal Ewingâs sarcoma.
175. CLASSIC
Case #390
28 year female with
soft tissue Ewingâs
sarcoma anterior thigh
Coronal proton density
MRI
195. Clear Cell Sarcoma
The clear cell sarcoma is thought to be a deep, non-cutaneous
variant of the pigmented melanoma. It is a very rare tumor affecting
females more than males. It is typically seen between the ages of
20 and 40 years. It usually occurs in tendon sheaths and fascial
planes, especially around the foot and ankle area, similar to the
clinical appearance seen with synovial sarcoma with which it can
be confused. The tumor usually begins as a slow growing lump that
has a benign appearance but after a period of several years the tumor
will start growing more rapidly and become painful. It has a high
potential to metastasize to local lymph nodes and to the lung.
Approximately 50% of patients with this tumor will be dead in five
years. The microscopic appearance is similar to that of the epithelioid
sarcoma, especially if melanin is not found in the specimen.
Treatment usually consists of wide local resection, if possible, but a
high local recurrence rate is common because of its location in
196. extracompartmental structures such as tendon sheaths. If that
occurs, 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 poor
prognosis but the response is usually not beneficial.
197. CLASSIC Case #393
35 year female with clear cell sarcoma hand
203. Myositis Ossificans
Myositis ossificans is a heterotopic ossification within muscle
fascial planes seen typically in young athletic individuals in their
adolescence and early adult life. It occurs primarily in males and
usually results from a significant injury to a muscle, such as a
tearing of the quadriceps muscle which is the most common
location for this problem. It is also seen in the gluteus maximus
and the brachialis muscle at the elbow. The calcification is typically
noted on x-ray three to four weeks after the injury. It tends to occur
at the periphery of the damaged muscle and hematoma is usually
seen in the central area. As the lesion matures the calcific rim
around the damaged muscle will appear as fairly mature bone
and the central area will remain radiolucent, giving the so-called
zonal pattern that is almost diagnostic of traumatic myositis
ossificans. This is the opposite of osteosarcoma of soft tissue that
has the most dense portion of the calcifying lesion occurring centrally
and the more lytic portion at the periphery of the lesion. Myositis
204. ossificans can also be seen in older patients with no history of
trauma in which case the clinician becomes concerned about the
possibility of a neoplasm such as a synovial sarcoma or soft tissue
osteosarcoma. Histologically, the lesion will have the appearance
of a healing fracture, including immature cartilage and bone
formation, along with hematoma in the early stages. In rare cases,
after a period of 25 or 30 years, these dormant lesions can reactivate
and develop into an osteosarcoma. Treatment usually consists of
rest until the lesion matures after six months, at which point the
patient is usually asymptomatic. There is no reason to remove the
lesion unless there is significant clinical disability related to
stiffness of the adjacent joint.
There is a hereditary congenital form of myositis ossificans
referred to as myositis ossificans progressiva, or the newer term-
inology is fibrodysplasia ossificans progressiva, that is typically
seen in children under the age of ten years. It presents with a
clinical picture of progressive fibroblastic proliferation and
205. subsequent calcification and ossification of subcutaneous fat,
muscles, tendons, appeneuroses, and ligaments. This condition can
be associated with symmetrical malformations of the digits with
microdactyly of the thumbs and great toes, sometimes associated
with a failure of segmentation of the digital bony structures. The
condition usually presents between birth and the first six years of
age. It is inherited as an autosomal dominant trait. Males and
females are equally affected and the calcification in soft tissues is
usually precipitated by a local injury to the soft tissue. It occurs
typically in the musculature of the back, shoulder, paravertebral
region and upper arms. Fusion of the tempromandibular joint can
be seen. If the respiratory muscles are affected, death can result
because of respiratory failure or pneumonia in early adult life. The
prognosis for survival is very poor and most patients die within the
first ten to fifteen years of life. Biopsy or trauma of the affected
areas should be avoided because of new lesions that might
develop. There is no effective treatment or this condition.
248. Pigmented Villonodular Synovitis
The etiology of pigmented villonodular synovitis (PVNS)
remains controversial. It presents as an inflammatory synovial
disease, usually involving only one joint, but histologically the
disease presents with histiocytic proliferation in the subsynovial
tissue that takes on the characteristics of a neoplastic condition
similar to that of a giant cell tumor. PVNS occurs typically in the
subsynovial tissue about major joints of the lower extremity in
patients between the ages of 20 and 40 years. The knee joint is the
most common site, followed next by the hip, ankle and foot. It is
rare to see this disease in the upper extremity. The histiocytic
proliferation in subsynovial tissues is similar to that seen in giant
cell tumor of tendon sheathes in the hand and foot., The clinical
picture in the knee joint is that of spontaneous swelling associated
with pain and synovial hypertrophy. Hemarthrosis can result in
massive swelling about the knee joint and can occasionally result
249. in juxta-articular erosion of bone, similar to what is seen in
rheumatoid synovitis. Other clinical conditions with a similar
presentation include hemophilia and coccydiomycosis. In fewer
than 10 % of cases this condition will present as a localized focal
mass in the suprapatellar pouch of the knee or high in the popliteal
space posteriorly that can masquerade as a neoplastic condition
such as a synovial sarcoma.
Treatment for the more generalized synovial involvement of
the knee joint or other lower extremity joints consists of a subtotal
synovectomy that in many cases can be performed through an
arthroscope. In more extensive cases an open procedure may be
necessary. The recurrence rate is fairly high, in the range of 30%.
In cases where multiple recurrences result, treatment with radiation
therapy in the neighborhood of 1500-3000 centigray by external
beam is used. Injectable isotopes have also been used for radiation
treatment of recurrent cases. Secondary arthritic changes, especially
in the knee joint, can occur as a late complication of this disease
250. and these changes could lead to a total joint replacement at the
age of 50 or 60 years. On very rare occasion, this disease can
convert to a neoplastic sarcoma with a high degree of giant cell
activity. This is similar to the conversion of a giant cell tumor to
a malignant sarcoma.