Myxoid liposarcoma of the ankle

Myxoid liposarcoma of the ankle

Myxoid Liposarcoma of the Ankle Liposarcomas are among the most common soft tissue sarcomas, but are rarely found in the foot or ankle. Certain types ...

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Myxoid Liposarcoma of the Ankle Liposarcomas are among the most common soft tissue sarcomas, but are rarely found in the foot or ankle. Certain types of liposarcomas, which range from well-localized low-grade entities to highly aggressive neoplastic lesions, may resemble common benign soft tissue lesions. Myxoid liposarcoma is the most common type of liposarcoma and is important to recognize and differentiate from a benign soft tissue lesion because it may be a limb-threatening and/or life-threatening tumor. A thorough literature review and perplexing case study of myxoid liposarcoma of the ankle is presented.

Matthew B. Werd, DPM 1 Donna-Jean DeFronzo, DPM 2 Adam S. Landsman, DPM, PhD3

Maria Surprenant, DPM 4 Marc Sakoff, DPM 5

Soft5 tissue tumors in the lower extremity have been well-documented (1-16). Accurate diagnosis and proper management of malignant soft tissue lesions is critical to minimize morbidity and/or mortality. Among malignant soft tissue lesions, liposarcoma is relatively common and may be limb-threatening and/or life-threatening, but has seldom been reported in the foot or ankle. Liposarcoma was first reported in 1857 by Virchow, who used the term myxoma lipomatodes, and described it as a tumor comprised of a mixture of myxoid and lipoid elements, arising from adipose tissue (1-3). Since then, numerous reports of liposarcoma have been documented in the literature (3-13). In 1954, Pack and Pierson reviewed 105 cases of liposarcoma and reported that 62% of liposarcomas occur in the lower extremity (4). Liposarcomas were found most frequently in the thigh (40%), and rarely occurred in the foot (2.7%) or leg (6.7%), as shown by the scattergram (Fig. 1). In 1962, Enzinger and Weiss reviewed 103 cases of liposarcoma, and reported that 74% of liposarcomas in the lower extremity were rnyxoid-type (5). In 1966, Reszel reviewed 222 cases of liposarcoma of the extremities and limb girdle from the files of the Mayo Clinic (2). Three cases out of the 222 cases of liposarcoma occurred in the foot (1.3%) and 30 cases in the leg (13.5%). In 1971, Thompson et at.

presented a review of soft tissue sarcomas involving the extremities and the limb girdles (6). This study found that liposarcomas involved the extremities and limb girdles in 23 of 32 cases (72.8%), 2 cases of 32 (6.25%) involved the ankle, and no cases were reported in the foot. Also in 1971, Spittle et at. reviewed 60 cases of liposarcoma and found that 68% of liposarcomas occur in the lower extremity (7). In 1972, Spray reviewed 53 cases of lower extremity tumors, out of 3000 tumorous lesions (8). In this study, only two cases of liposarcoma were reported, both of the knee. In 1975, Sawhney et at. reported a liposarcoma of the hand, and stated that, until 1970, only four cases of liposarcoma of the hand had been reported, reiterating that both upper and lower distal extremities appear to be rare sites for liposarcomas (9). In 1980, Berlin reviewed 2720 lesions excised by podiatric physicians and did not report a single case of liposarcoma (10). Berlin reviewed an additional 1870 patients who had soft tissue procedures in a hospital setting, and again did not report a single case of liposarcoma (10). In 1983, Das Gupta stated that liposarcomas are relatively common mesenchymal neoplasms, constituting 14.6% of all sarcomas of somatic tissues (3). In 1984, Berlin, in a larger study of 67,000 foot tumors and lesions that were excised in an office setting, again did not report a single case of liposarcoma (11). In 1985, Daniell presented a lO-year experience with 13 liposarcomas (12). Seven of 13 cases, 54%, occurred in the lower limb and buttocks. Enzinger and Weiss reviewed more than 3000 cases of liposarcoma and stated that, next to malignant fibrous histiocytoma, liposarcomas are the most common soft tissue tumors of adult life, and the true incidence rate of liposarcoma ranges between 10 and 12% of all soft tissue tumors (13). Enzinger and Weiss also discussed the

From the Department of Podiatric Surgery, HealthSouth Larkin Hospital, South Miami, Florida. 1 Submitted during second-year residency. Address correspondence to: 1100 Oakbridge Pkwy., 107, Lakeland, FL 33803. 2 Clinical Instructor, Scholl College of Podiatric Medicine, Chicago, Illinois. 3 Director of Research, Scholl College of Podiatric Medicine, Chicago, Illinois. 4 Submitted during first-year residency. 5 Attending physician, HealthSouth Larkin Hospital, South Miami, Florida. 1067-2516/95/3405-0465$3.00/0 Copyright © 1995 by the American College of Foot and Ankle Surgeons

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Figure 2. Anatomic locations of liposarcomas in a review of 1067 cases. (From Enzinger, F. M. and Weiss, S. W. (eds.), Soft Tis.sue Tumors, ~nd ed., p. 347, Mosby-Year Book, Inc., S1. LOUIS, 1988; reprinted with permission from Mosby-Year

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Figure 1. Scattergram showing distribution of liposarcomas in a review of 105 cases. (From Pack, G. T. and Pierson, J. C., Surgery 36:690, 1954; reprinted with permission of the

publisher, Mosby-Year Book, Inc.) Armed Forces Institute of Pathology's review of 1067 liposarcomas that were seen over a lO-year period (13). This study found that liposarcomas are primarily tumors of adults with a peak incidence between 40 and 60 years of age, and are virtually unknown in infants and small children. Although there was a propensity for liposarcomas to be more common in males, there was no known correlation between races or geographic locations. Only 5% of the lO67 liposarcomas in this study occurred in the lower leg (Fig. 2). Enzinger and Weiss developed a widely used histologic classification system of liposarcomas, which was actually modified from Stout's original classification in 1944 (13, 14). First, the stage oflipoblast development is judged by the relative amounts of lipid in the cells and of mucinous material in the extracellular spaces. Second, the overall degree of cellularity and cellular pleomorphism is considered. The four histologic subtypes, based on Enzinger and Weiss's classification, with clinical behavior of each type, is listed in Table 1 (13). Kirbyet al. reported an analysis of 83 cases of soft tissue tumors and tumor-like lesions of the foot, but did not report any cases of liposarcoma (15). Liposarcoma of the Foot or Ankle

Liposarcoma of the foot or ankle IS Important to recognize because it can be a limb-threatening and/or 466

Inguinal area· l 2%

life-threatening soft tissue mass. Myxoid liposarcomas been reported to be the most common type of liposarcoma, 40 to 50%, but have been reported infrequently in the foot or ankle (13, 16-21). Myxoid liposarcomas are most frequently seen in males between 40 ~o 60.years of age, and have only recently been reported In children (13). Reports of myxoid liposarcomas in the foot or ankle are rare, and literature concerning the management and outcome of liposarcoma treatment of the foot or ankle is very limited (Table 2). Sugar and Murphy (16) reported that no cases of liposarcoma of the foot had previously been reported; however, Pack and Pierson (4), in 1954, did mention two cases of liposarcoma of the foot, and one case of liposarcoma of the ankle. Sugar and Murphy were the first to report a detailed case of liposarcoma of the foot in a 40-year-old white male physician (16). The lesio~ appeared to have arisen after an incident of trauma to the plantar region of the foot. Surgical excision of the encapsulated mass was performed, with numerous "digitations" of the mass noted. Recurrence at 1 year was followed by below-the-knee amputation. Two years later, unexciseable vertebral metastases were found and radioactive cobalt therapy was initiated. Pulmonary and abdominal metastases with intestinal obstruction were later found, and the patient died 3 years after initial excision. Booker reported a case of myxoliposarcoma on the dorsum of the foot in a 46-year-old female (17). Surgical excision of the encapsulated mass was performed, but recurrence at 3 months was followed by below-the-knee amputation, and 11/ 2 years after the initial surgery, the patient died of pulmonary metastases. ~ave

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TABLE 1. Histologic classification and clinical behavior of liposarcomas as described by Enzinger and Weiss (13)8 Clinical Behavior

Liposarcoma Classification

1. Well-differentiated liposarcoma Low-grade malignancy and rarely metastasize (least aggressive and commonly mistaken for lipomas) Lipoma-like Sclerosing Inflammatory De-differentiated 2. Myxoid liposarcoma

Low-grade malignancy and may metastasize

3. Round cell liposarcoma

Highly aggressive lesions which commonly metastasize and yield less than a 20% 5-year survival rate

4. Pleomorphic liposarcoma Poorly-differentiated

Highly aggressive lesions which commonly metastasize and yield less than a 20% 5-year survival rate

8 From Enzinger, F. M. and Weiss, S. W. (eds.), Soft Tissue Tumors, 2nd ed., p. 353, Mosby-Year Book, Inc., SI. Louis, 1988; reprinted with permission from Mosby-Year Book.

TABLE 2. Reported cases of liposarcoma of the foot and ankle since 1954 Patient Age (years)

Case No.

Year of Report

1 2 3 4

1954 1954 1954 1955

Pack (4) Pack (4) Pack (4) Sugar (16)

NR NR NR 40

NR NR NR Male

NR NR NR Poorly differentiated

Foot Foot Ankle Foot: plantar

5 6 7 8 9 10 11 12 13 14 15 16

1962 1965 1966 1966 1966 1968 1971 1971 1978 1980 1988 1995

Enzinger (5) Booker (17) Reszel (2) Reszel (2) Reszel (2) Eisenberg (18) Thompson (6) Thompson (6) Kelly (19) Campbell (20) Wu (21) WERD et al.

NR 46 NR NR NR 51 56 50 56 NR 50 39

NR Female NR NR NR Female Male Male Female NR Male MALE

NR Myxoid NR NR NR Myxoid Myxoid Myxoid Well-differentiated NR Myxoid MYXOID

Foot Foot: dorsum Foot Foot Foot Foot: 1M space Ankle Ankle Foot: hallux Ankle joint Ankle ANKLE

Primary Author

Sex

Type

Site

Treatment Irradiation NR NR Wide excision + lrr NR Wide excision NR NR NR Wide excisions BKA Wide excision Wide excision NR Wide excisions Wide excision + Irr

Follow-up NR NR NR _8

NR _b

NR NR NR TF 10mo TF 5y TF 1y NR NR _c

TF 28mo

NR, Not Reported; TF, Tumor-Free; BKA, Below-the-Knee Amputation; Irr, Irradiation; 1M, Intermetatarsal; y, years; mo, months. Patient had recurrence at 1 year, treated with BKA, followed by inexcisable vertebral, pulmonary, and abdominal metastases, and died 3 years after initial excision. b Patient had recurrence at 3 months, treated with BKA, but died from pulmonary metastases 1% years after initial excision. C Patient had local recurrence 3 times in 6 years, but refused BKA. 8

Eisenberg reported a case of myxoid liposarcoma of the forefoot in a 51-year-old female (18). This patient had two previous surgical excisions of the mass and a biopsy that was initially interpreted as a lipoma. The recurrent lesion was surgically excised from the third intermetatarsal space, was noted to have small "grapelike elements," and was attached to surrounding soft tissue. Ten months after the last excision, the patient was still tumor-free. Thompson et at. presented two cases that involved the ankle (6.25%), out of 32 cases of liposarcoma (6). One patient was a 50-year-old male who was seen after 6 months of symptoms, received no medical treatment,

and was treated surgically with a below-the-knee amputation. This patient was still tumor-free after 5 years, when he then died of a perforated ulcer. The second patient was a 50-year-old male who was seen after 9 months of symptoms, received no medical treatment, and was treated surgically with a wide excision of the mass. The second patient was still living tumor-free 1 year after surgery. Kelly and Shramowiat reported a case of a welldifferentiated liposarcoma of the hallux in a 56-year-old black female (19). The patient had been treated for 4 years with injections and hydrotherapy and finally underwent excision of the mass. Margins were noted VOLUME 34, NUMBER 5, 1995

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TABLE 3. Oifferential diagnoses for myxoid liposarcoma

microscopically to be free from tumor, however, no follow-up evaluation was given. Campbell et ai. reviewed 20 primary liposarcomas of the lower extremity and reported one case contiguous with the ankle joint, but did not elaborate on this patient (20). Wu presented a case report of a myxoid liposarcoma of the anterior aspect of the ankle in a 50-year-old black male who was seen after the lesion had been apparent for several months (21). The mass was surgically excised, but the patient had three tumor recurrences over the next 6 years at the same site. This patient had no clinical evidence of metastases, and refused below-the-knee amputation.

Angiomyoma (15) Epidermal inclusion cyst (15) Epithelial sarcoma Extraskeletal myxoid chondrosarcoma Fibroma (15) Fibroxanthoma Ganglion cyst (40) Giant cell tumor of the tendon sheath Hemangioma (15) Intramuscular myxoma (25) Leiomyoma (41) Upoblastoma (13) Lipoma (42) Myxoid malignant fibrous histiocytoma Neurofibroma Pigmented villonodular synovitis Rheumatoid nodule Schwannoma Synovial cyst (15) Synovial sarcoma (15)

Clinical Presentation The typical clinical presentation of the primary myxoid liposarcoma consists of a large slowlygrowing tumor mass deep in the soft tissues, usually in the intermuscular or periarticular planes (3, 22). There is usually nothing characteristic about the clinical history of liposarcoma, with the first manifestation of the disease being an insidiously growing, deep-seated, poorly-defined mass that has usually reached a large size by the time the patient seeks treatment. No known etiology has been identified, but trauma has been implicated as a possible precursor. However, a definite history of trauma to the exact site of the tumor is extremely rare, and most investigators deny or are doubtful about the existence of such a relationship (2, 13). Pain, tenderness, or functional disturbances occur in 10 to 15%, usually a late presentation with large tumors (13). Diagnosis Differential diagnosis of myxoid liposarcoma should be based on a detailed history and a thorough physical examination. Adjunctive tests that may be indicated include plain film radiography, angiography, magnetic resonance imaging (MRI), and computed tomography (CT). Stess et al. suggest ultrasonography for preoperative imaging of soft tissue tumors of the foot (23). Definitive diagnosis is made by biopsy, and morc recently, by using fine needle aspiration (24). Differential diagnosis of myxoid liposarcoma may include any subcutaneous soft tissue mass, including but not limited to those shown in Table 3. Tests in combination with each other may prove most beneficial to an accurate diagnosis. Hashimoto et ai. reviewed 14,000 cases of soft tissue tumors and by utilizing radiologic, immunohistochemical, and ultrastructural evaluations, were able to differentiate myxoid liposarcoma from intramuscular myxoma (25). The diagnosis of liposarcoma without further qualification of the exact type of 468

liposarcoma is meaningless, and provides no clear information as to the likely behavior of the tumor (13). Plain film radiographic features of myxoid liposarcoma differ considerably, and largely depend on the histologic sub-class. Well-differentiated liposarcomas, like normal fat or lipomas, show well-delineated radiolucencies that can be clearly distinguished from surrounding muscle tissue. Myxoid, round cell, and pleomorphic liposarcomas, on the other hand, are usually less well-differentiated, but may stand out from normal tissues because of their greater density. Soft tissue density is usually a mixture of lucency and density, and radio-opaque foci, caused by calcifications, are occasionally seen (2). Myxoid liposarcomas, which are highly vascular, would be expected to be radio-opaque on angiographs. MRI and CT evaluation can further assist in the determination of the exact location, size, anatomical relationship, and density of the primary tumor, and may aid in effective surgical planning. London, et at. correlated the MRI features and histologic features of liposarcomas and stated that magnetic resonance appears useful for preoperative staging, and may be useful in detecting early recurrence (26). Sundaram et at. correlated clinical and histologic data with the MRI appearance of myxoid liposarcomas (27). They stated that an MRI examination generally reveals myxoid tumors to be encapsulated, noninfiltrating, and usually septated. Myxoid liposarcomas often demonstrate a predominantly low signal with a few amorphous or linear high signal foci on T1-weighted sequences, but show high signal intensity on T2-weighted sequences. The low signal seen on Tcweighted sequences of myxoid liposarcomas was explained by the fact that myxoid

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liposarcomas contain less than 10% mature fat. They found that histologic evaluation showed less than 10% mature fat in myxoid liposarcomas, which correlated with their low signal intensity on T1-weighted sequences. This contrasts with what is seen with the other types of lipomatous tumors, such as lipomas and lipoblastic liposarcomas, which, because of their greater content of mature fat cells, generally demonstrate predominantly high signal foci on Tcweighted images and low signal intensities on Tz-weighted images. Jelinek et at. studied MRI and cr findings in liposarcomas of the extremity and concluded that liposarcomas often contain no fat (28). Peterson et at. found that based on the MRI characteristics, differentiation of intramuscular myxomas from malignant neoplasms containing myxoid tissue was possible (29). On MRI examination, myxoid liposarcomas would be expected to have an appearance similar to that of ganglions and other soft tissue lesions, and therefore may not lead to a definitive diagnosis. Ganglions , which are fluid-filled, show a low signal intensity on T c weighted sequences and a high signal intensity on T zweighted sequences, and frequently arise from tendon sheaths and joints. Myxoid liposarcomas exhibit a very similar pattern on both Tcweighted and Tz-weighted images (29, 30). Pathologic Examination

Liposarcomas are usually between 5 to 10 em. in size at the greatest diameter and can become very large. Delameter reported a retroperitoneal liposarcoma weighing close to 200 pounds at the time of the patient's death (31). Upon gross examination , myxoid liposarcomas are generally divided into small, distinct lobules formed by fibrous septa , present in a variety of colors (generally white, yellow, or red) , and are somewhat more opaque than lipomas (13, 32). They are often pseudoencapsulated, which deceivingly suggests a benign state. While the primary tumor normally does not invade the muscle bellies, recurrent liposarcomas do invade and infiltrate the surrounding tissue (3). On cut section, liposarcomas characteristically have a mucinous gelatinous-type appearance with focal areas of hemorrhage (13). Enzinger and Weiss stated that myxoid liposarcomas are composed of three main tissue components, similar to fetal fat: first, proliferating lipoblasts in varying stages of differentiation; second , a delicate, plexiform, rich vascular network of small to medium-sized vascular channels mixed with variable amounts of lipoblasts, giving a "chicken-wire" or "signetring" appearance (the histologic hallmark of myxoid

liposarcoma); and , third, a myxoid matrix containing abundant nonprotein-linked and nonsulfated glycosaminoglycans or hyaluronidase-sensitive mucopolysaccharides (13). Treatment

Treatment of myxoid liposarcoma usually consists of wide local excision of the tumor. Careful examination of the margins of the specimen is necessary to avoid the recurrences that have been reported when the tumors are not completely excised (12, 20, 32). Daniell reviewed cases of myxoid liposarcomas and found that myxoid liposarcomas have a relatively long natural history with frequent episodes of local recurrence (12). His treatment recommendations for myxoid liposarcomas included primary compartmentectomy with radiotherapy, and he preferred to treat recurrences with amputation in addition to chemotherapy. Amputation may be necessary if multiple foci are found , and the general rule of amputating above the level of origin of the muscle groups involved is a good principle to observe (4). Campbell et at. reported on 62 patients who were treated for liposarcoma of the lower extremity, and recommended primary amputation for tumors contiguous to the ankle joint (20). They stated that a failure to control local disease may result in a local spread or blood-borne dissemination. High-dose intraoperative radiation, as an adjunctive treatment to help prevent recurrence, has been suggested, and postoperative radiation is a valuable adjunct to surgical therapy , especially for liposarcomas of myxoid-type (33-35). High-dose radiation is capable of retarding further growth and preventing local recurrence, and may obviate the need for amputation. The prognosis for these tumors depends on the location and extent of the disease. Patients with myxoid liposarcoma in the extremities have a better prognosis than those with tumors involving the retroperitoneum (22). Recurrence of liposarcoma is common. Azumi et at. reviewed 24 myxoid liposarcomas and found the overall recurrence rate to be 33%, and the rate of metastasis to be 25% (36). Increased cellularity or mitotic activity before the development of metastases was demonstrated in all lesions that metastasized. Liposarcomas, like other soft tissue sarcomas, primarily metastasize to the lung and less frequently to the liver and soft tissues. Klein and Desai consider myxoid liposarcomas to be well-differentiated low-grade tumors that rarely metastasize (37). Recurrence should become apparent within the first 6 months after initial excision (13). Wu reported on a case of myxoid liposarcoma in VOLUME 34, NUMBER 5, 1995

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Figure 3. Plain film radiographs showing an increase in soft tissue density of the myxoid liposarcoma over the anterior aspect of the ankle. A, lateral-oblique projection; B, lateral projection; C, ankle mortise projection; D, anteroposterior projection.

the ankle that recurred three times after surgical excision in 6 years of follow-up (21). Case Report History and Physical Examination

A 39-year-old man presented with a large mass on the anterior aspect of his left ankle that had been gradually increasing in size over the past year. The mass caused the patient pain in shoes, was aggravated by activity, and decreased total ankle joint range of motion to approximately 150 • The patient did relate a history of having sprained the left ankle about a year before. The mass was previously diagnosed as a ganglion cyst, and the 470

patient was advised to seek specialized medical attention should the mass continue to be bothersome. The mass did continue to cause pain, and the patient presented to these authors for follow-up. Physical examination revealed intact neurological, vascular, and integumentary status of both lower extremities. A large, firm, nodular soft tissue mass on the anteromedial portion of the left ankle was easily palpable. The mass appeared to be attached to underlying deeper structures, and was not freely moveable with active and passive range of motion of the ankle joint. The mass did not transilluminate; no edema, erythema, or warmth was noted. Popliteal and inguinal lymph nodes were palpated and were not tender or enlarged.

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Figure 4. Lateral view of sagittal plane magnetic resonance image slices at the level of the medial aspect of the ankle joint. A, T1-weighted sequence (TR = 500, TE = 35) showing the low signal intensity of the myxoid liposarcoma; B, T2-weighted sequence (TR = 1000, TE = 30) showing the high signal intensity of the myxoid liposarcoma; C, T2-weighted sequence (TR = 1000, TE = 30) that is one slice lateral (5.0 mm.) to the image in Figure 2B. Note the apparent involvement of the tibialis anterior tendon and tendon sheath.

Radiologic Evaluation

Radiographic evaluation of the left ankle revealed soft tissue swelling anterior and medial to the ankle joint (Figs. 3 A-D). There was no evidence of destructive bony changes or joint space involvement. MRI demonstrated a large area consistent with a fluid-filled mass located anterior to the ankle. The mass showed decreased signal intensity on Trweighted sequences and increased signal intensity on the Tz-weighted sequences (Figs. 4 A-C). Based on MRI evaluation, the mass measured approximately 5 em. in greatest diameter, with some septations and apparent fluid extension tracking into the tibialis anterior tendon sheath. All of these findings were consistent with the diagnosis of a ganglion cyst arising from a tendon sheath (38). Laboratory Studies

Laboratory studies included complete blood cell count, chemistry profile, urinalysis, prothrombin time, and partial thromboplastin time, which were all unremarkable. The only abnormal laboratory values included a low glucose level of 63 mg./dl. (normal 65 to 115), high triglyceride level of 178 mg./dl. (normal 30 to 150), high cholesterol level of 203 mg./dl. (normal less than 200), and high eosinophil level of 10% (normal 0 to 6%). No additional laboratory studies were performed.

Surgical Procedure

Gradual progression in size of the lesion, continued pain over the lesion, and limited function of the ankle joint were contributing factors in deciding upon wide surgical excision of the mass. A curvilinear skin incision of approximately 5.5 em. in length was made along the course of the tibialis anterior tendon at the level of the ankle joint. Anatomic dissection to the level of the mass was performed. Intraoperative findings included a multilobular soft tissue mass involving the distal portion of the tibialis anterior muscle. The appearance of the mass was not consistent with that of a ganglion cyst. The contents of the mass were not fluid-filled and did not have the typical "apple-jelly" appearance of a ganglion. There did not appear to be a stalk from the tibialis anterior tendon or from the ankle joint. Multiple neovascular channels contiguous with the mass were noted, and portions of the mass were infiltrating the distal portion of the tibialis anterior muscle. The mass appeared to be pseudoencapsulated, with a delicate membrane surrounding it. The borders of the mass were noted to be irregular with no distinct margins. Once meticulously isolated from all surrounding tissues, the mass was excised in toto. VOLUME 34, NUMBER 5, 1995

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Pathologic Findings - Gross

A

The specimen was an irregular oblong soft tissue mass that measured approximately 5.7 x 3.2 x 2.0 em. The specimen had a glistening serous-type external surface that blended into a fibrous fascial-like membrane in certain areas. The cut surface showed a mucoid gross texture with color variations ranging from a fleshy tan-gray to hemorrhagic. Pathologic Findings - Microscopic

The initial findings included a cellular neoplasm with a myxoid and chondroid matrix. Mitoses were not evident despite the slight cellular atypia and increased cellularity, which lead to a differential diagnosis including extraskeletal myxoid chondrosarcoma, low-grade myxoid liposarcoma, or synovial sarcoma. Microscopic examination revealed a proliferation of delicate capillaries, a myxoid matrix, multiple cystic spaces, and scattered lipoblasts. The photomicrographs of this case are shown in Figures 5 A-C, which exhibit the histologic characteristics of myxoid liposarcoma. These findings were all typical of the final diagnosis of myxoid liposarcoma, which was confirmed by the Armed Forces Institute of Pathology. Stains for S-lOO protein, cytokeratin, and epithelial membrane antigen were performed and were all negative, which is consistent with the diagnosis of myxoid liposarcoma. An S-lOO antigen stain was performed to rule out a tumor of neural, melanocytic, or chondroid differentiation. A cytokeratin stain was performed to rule out synovial sarcoma, and an epithelial membrane antigen stain was performed to rule out a tumor of epithelial differentiation (39). Postoperative Management

Upon confirmation of the diagnosis of myxoid liposarcoma, the patient was referred to a surgical oncologist, who immediately performed a second wide surgical excision. This second procedure was performed because on histologic evaluation, the free border of the mass was noted to have some cellular infiltration (Fig. 5 C). The patient was subsequently referred to a medical oncologist, who reported no clinical evidence of metastasis. No mass was palpated in the area of the surgical site, and no lymph nodes were palpable in the popliteal or inguinal areas. Postoperative high-energy electron beam radiation treatment was performed for the next 4 months. The dose at the completion of treatment was 6080 centigrays. The patient tolerated this treatment well without recurrence of the myxoid liposarcoma at the surgical site or at any distant site. The patient has had a disease-free follow-up status for 28 months post-initial 472

Figure 5. Histopathologic photomicrographs of the myxoid liposarcoma (Courtesy of Michael Kambour, MO). A, "Chicken-wire" appearance of multiple vascular channels, with infiltrating lipoblasts and multiple cystic areas (H & E x 100); B, immature lipoblasts. Note the myxoid nature of cells and mucinous background (H & E x400); C, free border of lesion noted with some cellular infiltration (H & E X400).

excision of the myxoid liposarcoma. No local recurrence or distant metastases have been found.

Discussion This case of myxoid liposarcoma of the ankle was clinically perplexing because it was a limb-threatening

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and/or life-threatening condition that initially resembled a ganglion cyst arising from a tendon sheath. Once the diagnosis of myxoid liposarcoma was made, a much more aggressive treatment plan was taken in order to save the patient's leg and/or life. This diagnosis prompted follow-up consultation, a second wide excision, and high-energy electron beam radiation treatment. This patient has been without recurrence or metastases of myxoid liposarcoma for 28 months. It is critical to inform the patient that the recurrence rate is high with this type of liposarcoma, and that further progression of the disease is potentially limbthreatening and/or life-threatening. Five-year survival rates for all liposarcomas have been reported to be between 57 and 70%, and lO-year survival rates range from 50 to 53% (13). However, the specific type and location of the liposarcoma directly affect the 5-year survival rates. The less aggressive types (myxoid and well-differentiated) have a much better prognosis than do the more aggressive types (round cell and pleomorphic). Enzinger and Weiss found the 5-year survival rate of liposarcomas of the retroperitoneum to be only 39%, while the 5-year survival rate of liposarcomas of the extremities was reported to be 71% (5). Because of the rarity of myxoid liposarcoma, it may not be considered in the differential diagnosis of a ganglion cyst or other common benign soft tissue lesions. In cases of an atypical presentation of a soft tissue lesion, however, myxoid liposarcoma should be considered as a possible diagnosis because of the morbidity and even mortality associated with it. Acknowledgments

The author would like to gratefully thank Michael Kambour, MD, HealthSouth Doctors' Hospital, for his critical review of this manuscript and his expertise and assistance with the photomicrography, and Jason R. Hanft, DPM, HealthSouth Larkin Hospital, for his critical review of this manuscript. References 1. Virchow, R. Edin Fall von bosartigen, Zum Theil in der Formdes Neurons auftretende Fettgeschwulsten. Virchows Arch. Path. Anat. 11:281, 1857. 2. Reszel, P. A Liposarcoma of extremity: 222 cases. J. Bone Joint Surg. 48A:229-244, 1966. 3. Das Gupta, T. K. Tumors of the Soft Tissues, pp. 31-39, AppletonCentury-Crofts, Norwalk, CT, 1983. 4. Pack, G. T., Pierson, J. C Liposarcoma. A study of 105 cases. Surgery 36:687-712, 1954. 5. Enzinger, F. M., Weiss, S. W. Liposarcoma: a study of 103 cases. Virchow Arch. 335A:367-368, 1962. 6. Thompson, D. E., Frost, H. M., Hendrick, J. W., Hom, R. C Soft tissue sarcomas involving the extremities and the limb girdles: a review. South. Med. J. 64:33-44, 1971.

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