DOI:10.2214/AJR.05.0141
AJR 2007; 188:1302-1305
© American Roentgen Ray Society
Acral Myxoinflammatory Fibroblastic Sarcomas: MRI Findings in Four Cases
José Antonio Narváez1,2,
Salutario Martinez1,
Leslie G. Dodd3 and
Brian E. Brigman4
1 Department of Radiology, Duke University Medical Center, Durham, NC.
2 Present address: Department of Radiology, Hospital Universitari de
Bellvitge-IDIBELL, Feixa Llarga s/n, Hospitalet De Llobregat, Barcelona, Spain
08907.
3 Department of Pathology, Duke University Medical Center, Durham, NC.
4 Department of Orthopaedic Surgery, Duke University Medical Center, Durham,
NC.
Received January 27, 2005;
accepted after revision March 27, 2006.
Address correspondence to J. A. Narvaez.
Abstract
OBJECTIVE. Acral myxoinflammatory fibroblastic sarcoma is a rare,
recently described, low-grade sarcoma that involves mainly the distal
extremities. The purpose of this study is to report the MRI findings in four
cases of acral myxoinflammatory fibroblastic sarcoma.
CONCLUSION. Acral myxoinflammatory fibroblastic sarcomas may present
with various MRI patterns that probably reflect their variable histologic
composition. Differential diagnosis with other benign conditions, especially
with ganglion cysts and giant cell tumors of the tendon sheath, may be
difficult. We report tumoral invasion of the bone in one case, which to our
knowledge has not been previously described.
Keywords: MRI • musculoskeletal imaging • sarcoma • soft-tissue neoplasms
Introduction
Acral myxoinflammatory fibroblastic sarcoma, also called
inflammatory myxohyaline tumor of the distal extremities, is a neoplasm of low
malignant potential characterized by a complex mixture of histologic elements,
including a variably cellular to hyalinized stroma that is inflamed, myxoid
nodules, and enlarged ganglion-like cells
[1,
2].
Acral myxoinflammatory fibroblastic sarcomas may occur in all age groups,
although most patients are in the fifth and sixth decades of life
[1-3].
Patients usually report a painless mass, most often in the subcutaneous
tissue. Lesions are located characteristically, but not exclusively, in the
distal extremities [4].
This entity has been mainly described in pathology journals, with only one
report of the MRI findings [5].
In this study, we report four cases of histology-proven acral myxoinflammatory
fibroblastic sarcoma, and we describe the MRI features.
Materials and Methods
We retrospectively reviewed the MRI features of acral myxoinflammatory
fibroblastic sarcoma. With this objective, we retrieved the files of all
patients with acral myxoinflammatory fibroblastic sarcoma seen at our
institution since 1998. This date reflected the first description of this
entity by three groups of investigators
[1,
3]. Five patients were found.
All patients had histologic proof of this tumor at surgical excision. Of
these, MRI was performed in four patients, two men and two women, with ages
ranging from 22 to 66 years (average age, 44 years), who form our study group.
Medical records were examined with regard to demographic data, presenting
symptoms, duration of symptoms, site of involvement, and type of surgical
treatment. Reports of biopsy specimens and radiographs were also reviewed.
The MRI studies were performed on different 1.5-T superconducting magnets
using a flexible extremity coil. The MRI sequences included T1-weighted
spin-echo images (TR range/TE range, 410-650/9-12) and fast spin-echo
T2-weighted images (5,520-3,100/60-89) with (n = 3) or without
(n = 1) fat saturation in all patients. Contrast-enhanced spin-echo
T1-weighted images (IV injection of 0.1 mmol/kg of gadopentate dimeglumine),
with (n = 2) or without (n = 2) fat saturation, were
obtained in three patients, and T2-weighted gradient-recalled echo images
(TR/TE, 500/20; flip angle, 20°) were obtained in one patient.
Axial and coronal planes were used in all cases, and the sagittal plane in
one case. The imaging matrix was 256 x 256, and the section thickness
was 3-5 mm with a 0.3- to 0.5-mm intersection gap. Two musculoskeletal
radiologists retrospectively reviewed the radiographs and MR images. MRI
criteria included lesion location; size; borders; and signal intensity on
T1-weighted, T2-weighted, fat-suppressed T2-weighted, and contrast-enhanced
T1-weighted images. The findings were reported as consensus opinions.
Results
All patients presented to a general orthopedist or hand surgeon with the
complaint of several months' (range, 3-36 months; mean, 14 months) history of
a palpable mass. Lesions were located in the hand, third finger, base of
fourth and fifth fingers, and shoulder abutting the acromioclavicular joint.
Clinically, each of the patients was thought to have a benign condition at the
time of the initial evaluation. The preoperative suspected diagnosis was
ganglion in two cases, giant cell tumor of the tendon sheath in one case, and
unspecified in the remaining case.
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Fig. 1A —44-year-old woman with painless mass in left hand of 3 years'
duration. Coronal T1-weighted MR image (TR/TE, 400/12) shows ovoid mass on
fourth interdigital space that was slightly hypointense to skeletal muscle.
Note complete peripheral isointense rim.
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Fig. 1B —44-year-old woman with painless mass in left hand of 3 years'
duration. Coronal fast spin-echo fat-suppressed T2-weighted axial MR image
(TR/TEeff, 6,200/60) shows mass to have homogeneous high signal
intensity.
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Fig. 1C —44-year-old woman with painless mass in left hand of 3 years'
duration. Coronal contrast-enhanced fat-suppressed T1-weighted MR image
(TR/TE, 440/12) shows strong enhancement of most of lesion, with peripheral
rim of decreased enhancement.
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In all four patients, lesions were marginally or intralesionally excised,
and pathology was consistent with acral myxoinflammatory fibroblastic sarcoma.
All tumors had in common the four elements that characterize acral
myxoinflammatory fibroblastic sarcoma: a proliferation of spindled,
fibroblastic sarcomatous cells; extracellular myxoid matrix material; a
superimposed inflammatory cell component; and the presence of the
"virocyte-like" or Reed-Sternberg-like cells.
In all patients, the more cellular and myxoid areas were divided into
nodules by dense, fibrous bands. In the more myxoid lesions, the cellular
components, both fibroblastic and inflammatory, tended to be concentrated at
the periphery of the nodules. The inflammatory component was composed of
plasma cells, neutrophils, and eosinophils. The sarcomatous cells, both
fibroblastic and virocyte-like, had relatively abundant cytoplasm and large
nuclei with prominent nucleoli. Mitosis was present but not frequent.
The patients were subsequently referred to an orthopedic oncologist for
further evaluation and treatment at our institution. In each case, the patient
was appropriately staged. No evidence of regional or distant metastatic
disease was found in any patient. A wide tumor bed resection was performed in
each patient, with negative margins obtained. No adjunct therapy was used.
Radiographs did not show abnormalities in two patients. A noncalcified
soft-tissue mass was seen on radiographs in two patients; in one of the two,
subtle bone erosion was also noted.
On MRI, these lesions were located mainly in the subcutaneous tissue of
three patients but extended through the fascia, into the muscle in two
patients and into the bone in one patient. Osseous involvement, detected on
radiographs as subtle bone erosion as previously stated, was better shown on
MRI. In the fourth patient, the lesion was located deep in relation to the
fifth extensor tendon compartment of the hand, beneath the extensor
retinaculum of the wrist. Lesional borders were well defined in two patients,
partially well defined in one patient, and ill defined and infiltrative in one
patient.
On T1-weighted sequences, three lesions were hypointense to skeletal
muscle, one with an isointense peripheral thin rim (Fig.
1A,
1B,
1C). In one patient, the tumor
was slightly hyperintense to skeletal muscle. Three lesions were homogeneous
and the fourth was heterogeneous on T1-weighted sequences.
On T2-weighted images, the tumor was hyperintense to fat in two patients
(Figs. 1A,
1B,
1C and
2A,
2B,
2C). In the third patient, the
lesion was predominantly hyperintense to fat but contained areas of
intermediate and low signal intensity (Fig.
3A,
3B,
3C,
3D,
3E,
3F,
3G); and in the remaining
patient, the lesion presented as a central hyperintense zone surrounded by a
peripheral thick rim of intermediate signal intensity. Gradient-echo recalled
T2-weighted sequences were available for this last patient and showed the
lesion to be homogeneously hyperintense, with loss of the peripheral,
intermediate-signal-intensity rim seen in the corresponding T2-weighted
sequence.
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Fig. 2B —49-year-old man with mass in right hand that is painful and tender
to palpation. Axial fast spin-echo fat-suppressed T2-weighted MR image
(TR/TEeff, 3,600/90) shows mass (arrows) of uniform high
signal intensity.
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Fig. 2C —49-year-old man with mass in right hand that is painful and tender
to palpation. Axial contrast-enhanced T1-weighted MR image (TR/TE, 550/14)
shows homogeneous enhancement of lesion (arrows).
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Fig. 3B —66-year-old man with painless mass in right middle finger. Axial
T1-weighted MR image (TR/TE, 550/10) shows lobulated mass on volar aspect of
middle finger. Signal intensity of mass is intermediate and hypointense to
skeletal muscle. Note adjacent bone infiltration (arrow) and
relationship of mass to tendon.
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Fig. 3C —66-year-old man with painless mass in right middle finger. Axial
fast spin-echo fat-suppressed T2-weighted MR image (TR/TEeff,
3,600/90) shows heterogeneous signal intensity of mass, with predominant areas
of high signal intensity interspersed with zones of intermediate and low
signal intensity. Note minimal increase of signal in adjacent phalanx.
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Fig. 3D —66-year-old man with painless mass in right middle finger. Coronal
contrast-enhanced fat-suppressed T1-weighted MR image (TR/TE, 650/10) shows
marked, mildly heterogeneous enhancement.
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Fig. 3E —66-year-old man with painless mass in right middle finger.
Photomicrographs of specimen show alternating fibrous (E) and myxoid
(F) regions of neoplasm, both with modest infiltrate of inflammatory
cells. (H and E, x100)
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Fig. 3F —66-year-old man with painless mass in right middle finger.
Photomicrographs of specimen show alternating fibrous (E) and myxoid
(F) regions of neoplasm, both with modest infiltrate of inflammatory
cells. (H and E, x100)
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Fig. 3G —66-year-old man with painless mass in right middle finger.
High-power photomicrograph of specimen shows mixture of acute inflammatory
cells and larger cells with vesicular nuclei. Note multinucleate giant cell in
background myxoid substance. (H and E, x200)
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Intense enhancement after the administration of IV contrast material was
observed in three patients; homogeneous enhancement, in two patients (Figs.
1A,
1B,
1C and
2A,
2B,
2C), one of whom had a
peripheral rim of decreased enhancement (Fig.
1A,
1B,
1C); and mildly heterogeneous
enhancement (Fig. 3A,
3B,
3C,
3D,
3E,
3F,
3G) in the third patient.
Discussion
Acral myxoinflammatory fibroblastic sarcomas are low-grade sarcomas of the
distal extremities that were described independently by three groups of
authors in 1998
[1-3].
The term "acral myxoinflammatory fibroblastic sarcoma" was
proposed by Meis-Kindblom and Kindblom
[1], whereas almost
simultaneously Montgomery et al.
[3] coined the descriptive term
"inflammatory myxohyaline tumor of distal extremities with virocyte or
Reed-Sternberg like cells" for the same lesion. Moreover, in the same
year Michal [2] reported an
"inflammatory myxoid tumor of the soft parts with bizarre giant
cells," which basically corresponds to the same entity.
In a search of the literature, we identified 132 cases of acral
myxoinflammatory fibroblastic sarcoma, most published in pathology journals
[1-11].
Seventy-five percent of the reported cases are found in the first two articles
describing this entity [1,
3]. Of these 132 cases, 72
patients (55%) were male and 60 (45%) female, with ages ranging from 4 to 87
years (mean, 35-53 years). In all reported cases, tumors were located in the
extremities. In 89 cases (67%), lesions were found in the upper extremity,
most commonly in the fingers or hand. The foot, ankle, and wrist were less
common anatomic locations
[1-3].
Because a percentage of cases were not acral in location, some authors
recommended avoiding the use of the adjective "acral" in the name
of this entity [4]. In this
respect, in one of our patients the tumor was located in the subcutaneous
tissue adjacent to the acromioclavicular region. Although several reported
cases of this entity have been described involving the proximal upper
[2,
7,
10] or lower extremities
[2,
4], to our knowledge no cases
have been reported near the acromioclavicular joint.
Clinically, this entity usually presents with slowly growing, painless
masses
[1-3].
Recurrences after surgical excision were common, with 38 reported patients
(29%) having at least one recurrence. Only three cases of metastasis (two
confirmed by pathologic diagnosis) to the inguinal lymph nodes and lung have
been reported [1,
11]. In one case, recurrence
and metastases were recognized rapidly, only 3 months after the first excision
[11]. The high rate of
recurrences may be because most of these lesions were believed to be benign
preoperatively, and the surgical margins were frequently inadequate
[1]. Post-operative radiation
therapy may be best reserved for patients who are most likely to undergo a
wide local excision with adequate tumor-free margins. Local recurrences may be
treated with surgery, radiation therapy, or chemotherapy
[1].
Histologically, acral myxoinflammatory fibroblastic sarcoma is
characterized by the combination of an inflammatory background, a prominent
myxoid component, the presence of enlarged atypical cells with prominent
nucleoli, and often a bizarrely shaped nucleus
[1,
3]. An inflammatory infiltrate
may obscure the neoplastic nature of the lesion and is commonly associated
with fibrosis and focal hemosiderin deposition.
Immunohistochemically, tumor cells were invariably positive for vimentin,
and inconsistently positive for CD68 and keratins
[4]. Most lesions were
subcutaneous, and they frequently infiltrated the synovium and the dermis
[1-7,
9-11].
However, to our knowledge bone invasion, as shown both on MRI and
pathologically in one of our patients, has not been previously reported.
The histologic differential diagnosis is broad and varied, depending on
whether the inflammatory, myxoid, or bizarre atypical component predominates
in the lesion. Conditions such as tenosynovitis, pigmented villonodular
synovitis, giant cell tumor of the tendon sheath, ganglion cyst, and sarcoma
containing myxoid stroma are the main elements of the histopathology
differential diagnosis.
Tateishi et al. [5]
described the MRI features of four cases of myxoinflammatory fibroblastic
sarcoma. In that series, lesions manifested as small, poorly circumscribed
masses having a multinodular appearance and involving the underlying tendons.
The signal characteristics and enhancement pattern of these lesions were
nonspecific.
In our series of four patients, we did not observe a common pattern of MRI
findings. Lesional signal intensities were similar to those of a cyst (low
signal intensity on T1-weighted images and markedly high signal intensity on
T2-weighted images) on unenhanced sequences in two cases (Figs.
1A,
1B,
1C and
2A,
2B,
2C). Contrast-enhanced
T1-weighted images more accurately reflect the truly solid nature of the
lesions in these patients. The other two patients predominantly or partially
showed hyperintensity with areas of intermediate or low signal intensity on
T2-weighted images (Fig. 3A,
3B,
3C,
3D,
3E,
3F,
3G).
Unlike the MRI findings reported by Tateishi et al.
[5], the lesions in our series
presented well-defined borders in half of the patients and were subcutaneously
located in three patients; but in two patients, muscle or bone invasion was
seen. Wide contact with a tendon, which may lead to a misleading diagnosis of
giant cell tumor of the tendon sheath (Fig.
3A,
3B,
3C,
3D,
3E,
3F,
3G), was seen in one of our
patients.
This variable MRI pattern most probably mirrors the variable pathologic
appearance of this tumor, with predominantly myxoid-containing or more
cellular lesions potentially mimicking a ganglion cyst on MRI, as in two of
our patients. Moreover, more heterogeneous lesions, especially if they are
near the tendons, may be mistaken for a giant cell tumor of the tendon sheath.
In this respect, the initial diagnoses of pigmented villonodular synovitis,
giant cell tumor of the tendon sheath, and chronic synovitis were reported in
the series of Meis-Kindblom and Kindblom
[1].
The differential diagnosis of a soft-tissue mass in the distal extremities
depends on the age of the patient and the exact anatomic location of the
lesion. In the hand and fingers, which are the most common locations of acral
myxoinflammatory sarcoma, ganglion cysts, epidermoid inclusion cysts, and
giant cell tumors of the tendon sheath are the most common soft-tissue masses
encountered in the clinical reviews
[12]. Malignant soft-tissue
tumors are uncommon in the distal extremities, with alveolar rhabdomyosarcoma,
epithelioid sarcoma, clear cell sarcoma, and synovial sarcoma being the most
frequent.
In conclusion, acral myxoinflammatory fibroblastic sarcoma of the
extremities is rare. This tumor has a predilection for the distal extremities,
and, in our limited experience, may be confused on MRI with some common benign
entities, especially with ganglion cysts and giant cell tumor of the tendon
sheath. In cases showing cystlike lesions in atypical locations, or complex
cystlike lesions of the distal extremities, gadopentetate dimeglumine may be
helpful in showing the true solid nature of acral myxoinflammatory
fibroblastic sarcomas. Knowledge of the variable range of MRI features of
acral myxoinflammatory fibroblastic sarcoma is therefore important.
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Abstract
Introduction
