MRI is the imaging modality of choice for the local staging and posttreatment follow-up of soft tissue sarcomas. Along with clinical history and epidemiologic knowledge of various tumors, MRI findings can help narrow the differential diagnosis. This article reviews the imaging features of soft tissue and bone sarcomas of the upper extremities.
is the Section Chief of Body CT, University of Massachusetts
Memorial Medical Center, and Staff Radiologist, Massachusetts
is a Fellow in Pediatric Radiology, Massachusetts General
Hospital, Boston, MA.
is the Chief of Body Imaging,
is a Resident in Radiology, and
is a Staff Radiologist, Department of Radiology, William Beaumont
Hospital, Royal Oak, MI.
Magnetic resonance imaging (MRI) is the imaging modality of
choice for the initial imaging and posttreatment follow-up of
sarcomas. Though imaging alone cannot usually reliably predict the
histopathologic diagnosis or distinguish benign from malignant
processes, imaging features, along with clinical history and
epidemiologic knowledge of various tumors, can help narrow the
differential diagnosis. This review of sarcomas of the upper
extremities addresses the imaging features of soft tissue as well
as bone sarcomas.
Sarcomas are a group of malignant tumors arising embryonically
from primitive mesoderm. The primitive mesenchymal tissue within
the mesoderm differentiates into various connective tissues of the
body, ie, tendon, ligament, muscle, and bone. Tumors of these
connective tissue elements are referred to as sarcomas. The
differentiation is not precise and, thus, some sarcomas have
ectodermal and epithelial origin. The majority of sarcomas arise
spontaneously, though a selected few have associated risk
Imaging of any soft tissue tumor should begin with conventional
radiography, followed by MRI as a second-line diagnostic technique-
before biopsy is performed.
A plain radiograph can help to determine if the soft tissue tumor
involves bone and to identify vascular calcifications within
hemangiomas, ossifi- cation within myositis ossificans, and
juxta-articular osteocartilaginous masses within synovial
MRI provides superior soft tissue contrast, allows multiplanar
image acquisition, eliminates exposure to ionizing radiation,
obviates the need for ionic contrast agents, and is not associated
with streak artifacts, as are seen with computed tomography (CT).
Multiple investigators have shown that MRI is superior to CT in
revealing the extent of soft tissue tumors and the involvement of
adjacent neurovascular structures.
Though MRI is superior at locating and staging soft tissue tumors,
it remains limited in its ability to precisely characterize soft
tissue masses, since most lesions have prolonged T1 and T2
relaxation times. Another important limitation of MRI is its
relative inability to detect soft tissue calcification.
Tumors that are large, heterogeneous, and deep and that breach
anatomic barriers are more likely to be malignant. Soft tissue
masses in which MRI is strongly diagnostic include fatty tumors,
nerve sheath tumors, hemangiomas, pigmented villonodular synovitis,
The most important role of MRI is in defining the extent of a
lesion and its relation to adjacent anatomic structures. Extensive
peritendinous growth and in-termediate signal on T2-weighted
imaging (T2WI) suggests malignancy. The MR features are useful in
detecting tumor recurrence after surgery.
Utilizing MRI, lesions should be evaluated in at least 2
different orthogonal planes with conventional T1-weighted and
T2-weighted spin-echo MRI pulse sequences. Gradient echo may be a
useful sequence for the identification of hemosiderin.
A short tau inversion recovery (STIR) sequence can also be a
helpful adjunct, as it produces fat suppression and further
enhances signal intensity of abnormal tissue. It is especially
helpful for the detection of subtle abnormalities.
Fat suppression on T1-weighted imaging allows separation of
contrast enhancement and paramagnetic substances from fat. Fat
suppression on T2WI increases signal-to-background intensity
differences for high-signal lesions within fatty soft tissue and
Intravenous contrast is useful in finding a demarcation between
tumor and muscle/edema. It also provides information about tumor
vascularity and can distinguish solid from cystic lesions. With
gadolinium-enhanced MRI, early and rapid rim enhancement with
delayed central enhancement is more likely to be associated with
Malignant fibrous histiocytoma
Malignant fibrous histiocytoma (MFH) is the most common soft
tissue sarcoma in adults, comprising 20% to 40% of soft tissue
sarcomas. They have a 2:1 male predominance and occur most commonly
in patients 32 to 80 years of age (mean age 59 years). Malignant
fibrous histiocytoma can be found anywhere in the body, but 75% of
lesions occur in the extremities, with the greatest number in the
lower extremities and roughly 15% in the upper extremities.
Malignant fibrous histiocytoma presents as a painless soft tissue
mass. The risk factors for MFH include radiation therapy, metallic
foreign bodies (ie, shrapnel), and metallic orthopedic hardware.
On radiography, MFH appears as a soft tissue mass containing
mineralization in 5% to 20% of lesions.
On MRI, MFH appears as a well-circumscribed, lobulated, large mass
with heterogeneous signal on all sequences due to different
histologic patterns within the lesion (Figure 1). On T1WI, MFH has
intermediate signal; and on T2WI, the lesions have high signal with
marked enhancement on postcontrast images. Similar to synovial
sarcoma, deep MFH can cause extrinsic erosion of adjacent bone.
Liposarcoma is the second most common soft tissue sarcoma,
accounting for 17% of soft tissue sarcomas. Liposarcoma has a 1.2:1
male predominance and occurs most commonly in the fifth to sixth
decade of life. Though liposarcoma most commonly occurs in the
lower extremities, it occurs in the upper extremities in roughly 7%
On radiography, liposarcoma appears as an indistinct soft tissue
mass. The fatty component may be recognized occasionally; <10%
of lesions exhibit calcifications. There are 5 histologic types,
and MRI findings vary depending on the type. Well-differentiated
liposarcoma (the most common type) appears as a heterogeneous
lipomatous mass with nonadipose septal and nodular areas (Figure
Well-differentiated liposarcoma resembles a lipoma and, thus, shows
high signal on T1WI and low signal on T2WI. The nonadipose septal
and nodular regions have variable signal and enhancement with
The myxoid, round cell, and pleomorphic types have much less
adipose component, with only 50% of lesions showing fat
characteristics on MRI. Myxoid liposarcomas tend to be homogeneous
and may mimic cysts. Dedifferentiated liposarcoma is a bimorphic
sarcoma with both well-differentiated liposarcoma components and a
second nonadipose sarcoma.
Leiomyosarcoma is the third most common soft tissue sarcoma.
Leiomyosarcoma has a 1.2-2:1 male predominance and most commonly
occurs in the retroperitoneum, closely followed by the lower
extremities. They occur in the upper extremities in approximately
5% of cases. The age range is 35 to 79 years, with a mean age of
In the extremities, they typically present as a solitary painful
On radiography, they appear as an indistinguishable soft tissue
mass with rare calcifications or invasion of adjacent bone. On MRI,
they appear as a nonadipose soft tissue neoplasm with areas of
Malignant peripheral nerve sheath tumors
Malignant peripheral nerve sheath tumor (MPNST) is a high-grade
sarcoma that accounts for 10% of soft tissue tumors. Malignant
peripheral nerve sheath tumors are equally common in men and women.
They occur in an age range from 17 to 70 years, with a mean age of
They can involve any peripheral nerve, though larger nerve groups
are more commonly affected (ie, sciatic).
Individuals with NF1 are at increased risk for developing MPNST,
and, on average, these patients present with disease 10 years
earlier. Between 25% and 75% of patients who develop MPNST have
NF1. Radiation exposure has also been associated with MPNST. They
most commonly occur in the lower extremities and occur in the upper
extremities in roughly 11% of cases. Patients with NF1 typically
present with rapid enlargement of neurofibroma, along with pain and
Radiographs may reveal an ovoid or fusiform soft tissue mass.
These tumors are rarely mineralized and rarely affect adjacent
bone. On T1WI, the MPNST has low signal, and on T2WI, it has high
signal. Malignant peripheral nerve sheath tumor enhances brightly
on postcontrast images and often has a central dark area secondary
to necrosis and hemorrhage (Figures 3 and 4).
These tumors are continuous with the involved nerve.
Synovial sarcoma accounts for 5% to 10% of all malignant soft
tissue tumors. They occur equally often in both sexes and have a
tendency to occur in a younger population, ranging from 14 to 58
years of age (mean age 32 years). They occur in a variety of
locations, most commonly in the lower extremities, and involve the
upper extremities in roughly 13% of cases. Synovial sarcoma
involves the articular surface in only 10% of cases.
Radiographs reveal a soft tissue mass in 5% of cases, while the
remaining patients have normal examinations. One third of cases
have calcifications within the lesion, and 10% to 20% involve
adjacent bone. On MRI, there is heterogeneous signal with T1WI
indicating isointense signal to muscle. On T2WI, they are
heterogeneous with signal ranging from hypointense to hyperintense
relative to fat (triple signal). They enhance heterogeneously on
postcontrast images, and up to 40% of lesions have hemorrhage.
Fluid-fluid levels are seen in 10% to 25% of the lesions (Figure
The MR appearance most suggestive of synovial sarcoma is an
inhomogeneous septated mass with infiltrative margins located close
to a joint, tendons, or bursa, especially if soft tissue
calcification can be seen on radiography.
Rhabdomyosarcomas make up 2% of all malignant soft tissue
tumors. The male to female ratio is approximately 1.2:1. Their age
distribution is from 2 to 40 years (mean age 18), and the 2 peaks
of incidence are between the ages of 2 and 5 years and from 16 to
18 years. They occur in a variety of locations, most commonly in
the head and neck, followed by the lower extremities; they occur in
the upper extremities in 9% of cases.
Radiography reveals a soft tissue mass. MRI shows a diffuse soft
tissue mass displacing adjacent soft tissues. On T1WI, the lesion
has low-to-intermediate signal, and on T2WI, it has a high signal
with marked enhancement on postgadolinium images (Figure 6).
The other soft tissue sarcomas include epithelioid sarcoma
(Figure 7) and angiosarcoma (Figure 8). They most commonly occur in
young adult and middle- aged men, respectively.
Osteogenic sarcoma is the most common primary malignant bone
tumor in children; 75% of cases occur between the ages of 10 and 25
years. The majority (86%) of tumors occur in the long bones, with
the distal femoral metaphysis accounting for almost half of cases.
The proximal tibia and humerus are the next most common sites of
involvement. Within the long bones, more than half of the tumors
occur in the metaphysis, roughly another third in the
metaphyseal/epiphyseal site, and <10% occur isolated in the
On radiography, the tumor is most commonly a mixture of
osteolytic and sclerotic lesions that cause destruction of bone and
cortex with extension into soft tissue. There is a wide zone of
transition with an aggressive periosteal reaction and elevation of
periosteum from cortical bone (Codman's triangle). On MRI, both
intramedullary and soft tissue components exhibit low signal that
is usually homogeneous, although it can be heterogenous. On T2WI,
both intramedullary and soft tissue components have high signal
that is typically heterogeneous (Figure 9). Osteosarcoma has
variable enhancement with contrast and may have fluid-fluid levels
(Figures 10 and 11).
Ewing's sarcoma is the second most common primary malignant bone
tumor of children, following osteosarcoma. It is more common in
males than in females and has a peak incidence between 5 and 10
years of age. It occurs in long bones (Figure 12) in 50% of cases
and in flat bones in 40% of cases. As with osteosarcoma, it occurs
in the femoral diaphysis most frequently. Other common sites
include the humerus, pelvis, ribs, tibia, and scapula.
On radiographs, there is cortical bone erosion with a wide zone
on transition and, rarely, sclerosis. Typically, there is a
periosteal reaction that is laminated ("onion-skin" appearance)
with perpendicular speculations ("hair-on-end" appearance). There
is usually a soft tissue mass with rare calcifications. On MRI,
Ewing's sarcoma may have a heterogeneous or homogeneous
ap-pearance, with low-to-intermediate signal intensity on T1WI and
high signal on T2WI.
Chondrosarcoma is a primary malignant tumor derived from
cartilage cells, which arise de novo, or as secondary
chondrosarcoma due to malignant transformation of an exostosis or
enchondroma. They have a male predominance and an average age range
from 40 to 70 years. They typically develop in the shoulder, pelvic
girdles, and proximal long bones, and they typically occur as
central lesions within the intramedullary cavity.
On radiography, chondrosarcoma is a radiolucent lesion with
permeative borders, which often exhibit fluffy/flocculent
calcifications, endosteal scalloping, and periosteal reaction. MRI
shows low signal on T1WI and, on T2WI, shows homogeneous or
heterogeneous high-signal mass with a lobular configuration, with
or without thin low signal intensity septa.
MRI is the imaging modality of choice in the local staging of
soft tissue sarcomas and can often differentiate tumor from
tumorlike conditions. It cannot always differentiate benign from
malignant processes, although it is occasionally strongly
diagnostic for several soft tissue tumors. The most important role
of MRI for soft tissue tumors is in defining the extent of the
lesion and its relationship to adjacent anatomic structures.