3. Desmoid Tumor
One of the most common benign soft tissue tumors is the extra-
abdominal desmoid tumor, sometimes referred to as an aggressive
fibromatosis or simple desmoid tumor. As compared to the multitude
of different clinical types of infantile fibromatosis, the desmoid
tumor occurs in older children or young adults up through the age
of 40 years. The abdominal desmoid tumor is usually seen in young
adult females following pregnancy, whereas the extra-abdominal
desmoid tumor is found more commonly in men, usually in the
proximal parts of the body such as the shoulder, buttock and posterior
thigh area. Other areas include the popliteal space, the arm and
forearm. They are usually solitary lesions, however multi-centric
involvement can occur. In the case of “Gardner’s syndrome” the
desmoid tumor can be associated with polyposis of the large bowel
and cranial-facial osteomas. Desmoid tumors take their origin from
muscle fascial planes and tend to be extensively infiltrative into the
surrounding tissue with poorly defined margins that make surgical
4. resection difficult. They can also occur in tendon sheaths, joint
capsules, and even inside bone. Clinically, the desmoid tumor has
the appearance of a low grade fibrosarcoma but tends to be more
invasive in character and can frequently engulf adjacent neuro-
vascular structures. Even though the desmoid tumor has a histo-
logical appearance similar to a low grade fibrosarcoma, it will
never metastasize to distant parts but can be multifocal in its
presentation in the extremity. Clinically, the desmoid tumor is
very firm to palpation. It frequently causes symptoms of pain and
is tender on deep palpation. Microscopically the tumor is heavily
collagenized but with a very low mitotic index, with an appearance
similar to plantar fibromatosis.
The desmoid tumor does not calcify but is radiodense on ordinary
radiographs and can be easily identified on a soft tissue window CT
scan. The MRI is the best imaging study for this tumor and will be
low signal on the T-1 weighted image but only intermediate high
signal on the T-2 because of the low water content in this tumor
5. which helps separate it from malignant MFH and fibrosarcoma.
The desmoid tumor is related to physical activity compared to
higher grade spindle cell tumors that are more spontaneous in origin.
Treatment consists of a wide surgical resection, if possible, but
because of the high recurrence rate (about 50%), most clinicians
will advise post operative radiation therapy to the extent of 5000
centigray to the surgical site starting two weeks after surgery. This
reduces the chance of local recurrence to 10-15%. In rare situations
where the patient has multiple recurrences locally following RT,
amputation may be indicated. Even with amputation, recurrences
will be seen at the amputation site. In patients over 40 years of age
it is not unusual to see a spontaneous involution of desmoid tumors
requiring no treatment whatsoever. Estrogen may play a role in the
development of desmoid tumors and this accounts for the use of
tamoxifen with some reported clinical benefit. Other adjuvant
therapies include nonsteroidal anti-inflammatory agents and even
the use of mild chemotherapeutic agents.
6. CLASSIC Case #250.1
Axial T-1 MRI
50 year male with desmoid tumor thigh
86. Elastofibroma
The elastofibroma is seen almost exclusively in people past the
age of 55 years. It is more common in women than men, and the
majority of cases are seen in those involved in heavy manual labor
or unusual sports requiring extensive use of the upper extremities.
It almost always occurs between the scapula and the chest wall
inferiorly and is bilateral in about 10% of cases. It is usually located
in the lower subscapular area, deep to the rhomboid and latissimus
dorsi muscles where it is firmly attached to the chest wall in the area
of the seventh and eighth ribs posteriorly. Grossly, the tumor has an
appearance similar to a desmoid tumor and microscopically there is
an intertwining of swollen eosinophillic collagen fibers and elastic
fibers in an equal proportion. The elastic fibers have a degenerated,
beaded appearance or are fragmented into small globules or droplets
that are easily seen with the Verhoeff stain that is specific for elastin
fiber. The cross section shows a characteristic serrated edge. The
87. elastofibroma is considered a reactive pseudotumor with an excellent
prognosis. It is treated by a marginal surgical resection with an
extremely low recurrence rate and in some cases can be treated by
radiation therapy alone without surgery.
88. CLASSIC Case #255 Axial T-1 MRI
50 female with subscapular elastofibroma
97. Nodular Fascitis
Nodular fascitis is a very common, self-limiting, reactive process
rather than a true neoplasm occurring in young adults. Typically it
arises spontaneously and rapidly in the subcutaneous portion of the
lower aspect of the forearm and is associated with inflammatory
pain, swelling and local tenderness. Histologically, nodular fascitis
can take on the appearance of a spindle cell sarcoma. The lesion
grows quite rapidly over a period of several weeks, is usually
solitary, and usually occurs in the upper extremity. It is usually less
than 3 cm in diameter, has a grayish-white appearance and can have
myxoid changes. Histologically, the lesion is a fibroblastic pseudo-
tumor similar to granulation tissue with a fair number of mitotic
figures but no atypical mitoses will be seen. The fibroblasts are
infiltrated by lymphocytes. Treatment consists of local surgical
excision with a rare recurrence rate of less than 2%. No adjuvant
therapy is indicated.
98. CLASSIC Case #256
25 year female with nodular fascitis forearm
103. Plantar Fibroma
The plantar fibroma is a fairly common clinical entity similar to
to the palmar fibroma. It arises from the plantar fascia and is usually
located on the medial portion of the arch of the foot. As opposed to
palmar fibromatosis that is typically seen in older patients, the plantar
fibroma is more common in young adults or even in children. In
some cases, there is a familial background (this is particularly true
in Scandinavians), with a greater incidence in males. The plantar
fibroma is frequently asymptomatic in which case surgical treatment
is not indicated. However, if pain results, especially if pressure on an
adjacent central nerve causes symptoms, a simple surgical resection
can be performed. Both the palmar and plantar fibromas have a
characteristic fibrotic histological appearance that is quite cellular
in areas and can be misdiagnosed as a malignant sarcoma. Some
patients will have fibromas in their hands and feet simultaneously
and can also have penile fibromas. A contracture of the finger is
typical in palmar fibromas whereas toe contractures are not seen in
plantar fibromatosis.
104. CLASSIC Case #257
32 year female with plantar fibroma
110. Malignant Fibrous Histiocytoma
The malignant fibrous histiocytoma (MFH) is the most common
high grade soft tissue tumor. It occurs typically in older patients past
the age of 50 years and is more common in men. The most common
type is the so-called storiform or pleomorphic malignant fibrous
histiocytoma, followed next by the myxoid, giant cell, and inflamma-
tory subtypes. The pleomorphic form is seen in patients between the
the age of 50 and 70 years, and is usually found in a deep location in
a large muscle about the thigh, hip or retroperitoneal area. These
tumors usually present with symptoms of pain along with a tumor
mass that has been present for at least 3 or 4 months, but sometimes
these lesions can be asymptomatic. The gross appearance of the
tumor is a multinodular lesion that can have separate satellite lesions
located within the same muscle belly, usually at the upper or lower
pole of the lesion. On MRI, the lesion may demonstrate central
necrosis. The color is a dirty gray to reddish tan. Because this tumor
111. is usually high grade, it demonstrates a high index of mitotic activity
and the cell types usually found are malignant fibroblasts mixed
with anaplastic pleomorphic histiocytes. This tumor has a high
potential to metastasize to the lung in about 40-45% of cases. It can
go to regional lymph nodes in 10% of cases. With appropriate
surgical and adjuvant therapy, the local recurrence rate is in the
neighborhood of 10-15% after a wide surgical resection. When these
tumors are located in a superficial, subcutaneous location and
present with a size less than 5 cm, the overall prognosis is much
better, with only a 20% chance of metastasis to the lung. However, in
the more common, deeply located lesions that measure over 5 cm in
diameter, the overall survival rate is 55%.
The usual treatment for the high grade MFH is a wide surgical
resection when possible. If the tumor is too large and cannot be
resected safely because of major neurovascular invasion or multiple
compartmental contamination, an aggressive high level amputation is
sometimes indicated. Following surgical resection, most patients
112. with the more aggressive lesions will be treated with adjuvant
postoperative radiation therapy, in the neighborhood of 6500 centi
gray to the tumor site, with a wider field of 5500 centigray outside
the surgical site. At some institutions, patients will be treated with
preoperative radiation therapy, up to about 5500 centigray, with
an additional 1000 centigray being delivered two weeks after
surgery. The use of adjuvant chemotherapy for high grade soft tissue
sarcomas is quite controversial because there is minimal data to
suggest that the prognosis is significantly improved with its use.
Medical oncologists tend to discourage the use of this adjuvant,
especially in older patients who cannot tolerate the high toxicity
levels of current protocols.
The myxoid variant of the MFH is the second most common
type of MFH. Grossly it has a myxoid appearance and, because of
this, the chance of local contamination at the margins (with local
recurrence) is much higher. However, the metastatic rate to the lung
is only 25% giving the patient a better prognosis for survival.
113. The giant cell variant, occurring in large muscle groups in older
patients, has a tendency to be a hemorrhagic tumor with a high
pulmonary metastatic rate of 50%. The inflammatory MFH is also
seen in older patients and is more common in the retroperitoneal
area, with a 50% metastatic rate to the lung.
136. Case #259.1 MFH Thigh Axial CT scan
posterior
11-08 11-08
40 yr male with multiple surgeries over last 7 yrs for soft tissue MFH
of posterior thigh and distal femur with this recurrence in 11-08
137. 3-2010
Cor T-1 T-2
Local recurrence over 1 year post AK amp and RT
193. Case #1175 Sagittal T-2 MRI showing fluid-fluid level
37 year female with recurrent hematoma from injury
16 years ago looking like hemorrhage into an MFH
226. Case #1178.5 Recurrent Fibromyxoid Sarcoma of Arm
Axial T-2 Gad
50 yr female with history of soft tissue tumor resected from medial
aspect of arm followed with RT 6500 rads 1 yr ago
229. Fibrosarcoma
The soft tissue fibrosarcoma is clinically very similar to the MFH,
except for the absence of malignant-appearing histiocytes. The
fibrosarcoma is less common compared to the MFH and occurs in a
slightly younger age group between the ages of 30 and 55 years,
with equal involvement in males and females. This tumor can be
very low grade, similar to a desmoid tumor, in which case it grows
slowly and is relatively painless. The high grade lesions are faster
growing, more painful and carry a worse prognosis. These tumors
tend to affect deep fascial structures, around muscles in the area of
the knee and thigh, followed next by the forearm and leg. Grossly,
the fibrosarcoma has a firm lobulated pattern with a yellowish-white
to tan coloration. Occasionally, there will be calcific ossifying
deposits seen on x-ray examination. Histologically, the fibrosarcoma
is composed of spindle cells that form collagen fiber with varying
degrees of mitotic activity from grade I through grade III or IV,
230. but there are no malignant histiocytes seen the fibrosarcoma.
The treatment and prognosis depends on the grade of the tumor,
with the grade I lesions behaving much like a desmoid tumor with a
very slight potential for pulmomary metastases, whereas the grade
IV have a high potential for metastasis to the lung in about 50-60%
of cases. It is rare to see lymph node involvement. Treatment
consists of wide surgical resection. With the larger deep lesions,
resection is usually followed by local radiation therapy to the extent
of 6500 centigray, however the use of adjuvant chemotherapy is
considered controversial. As in the treatment of MFH, chemotherapy
is not usually advocated by medical oncologists.
231. CLASSIC Case #266 Axial T-2 MRI
41 year male
fibrosarcoma
forearm
249. Dermatofibrosarcoma Protuberans
The dermatofibrosarcoma protuberans is considered a low to
intermediate grade fibrohistiocytic tumor characteristic in its nodular
cutaneous location and occurring far more often in males then in
females, in a young to middle-aged adult population. It is most
commonly found in the trunk or proximal extremities and can be
associated with antecedent trauma in about 15% of cases. It usually
comes on gradually as a subcutaneous nodule that is relatively
painless and therefore patients may not present to a physician for
treatment for many years. Histologically, the tumor consists of low
grade spindle cells without evidence of mitotic activity and low
grade histiocytes. The spindle cell pattern is typically a storiform
one, similar to the fibrosarcoma and MFH. The tumor tends to invade
into the adjacent subcutaneous fat and skin and requires a very wide
surgical resection to avoid a high local recurrence rate. The chance
of pulmonary metastasis, however, is very low (1%). With a success-
ful wide resection there is no need for adjuvant therapies.
250. CLASSIC Case #268
30 year male with dermatofibrosarcoma protuberans
on the bottom of the heel
