Extract
Patients commonly present to their surgeon with a soft-tissue mass of an extremity or the torso. With an annual incidence of approximately 300 benign soft-tissue tumors, compared with only two malignant soft-tissue tumors, per 100,000 people in the United States, the majority of orthopaedic surgeons most frequently encounter benign soft-tissue masses. In order to avoid missing one of the 6000 malignant soft-tissue tumors that are diagnosed annually in the United States, orthopaedic surgeons must recognize the features key to differentiating benign from malignant tumors. The purpose of this lecture is to point out those key features and to outline an approach for physicians in evaluating soft-tissue masses.
Patients commonly present to their surgeon with a soft-tissue mass of an extremity or the torso. With an annual incidence of approximately 300 benign soft-tissue tumors, compared with only two malignant soft-tissue tumors, per 100,000 people in the United States, the majority of orthopaedic surgeons most frequently encounter benign soft-tissue masses. In order to avoid missing one of the 6000 malignant soft-tissue tumors that are diagnosed annually in the United States, orthopaedic surgeons must recognize the features key to differentiating benign from malignant tumors. The purpose of this lecture is to point out those key features and to outline an approach for physicians in evaluating soft-tissue masses.
Unfortunately for diagnosticians, the epidemiological and clinical features of patients presenting with a malignant soft-tissue tumor do not differ substantially from those of patients with a benign soft-tissue tumor. Although carcinomas can metastasize to soft tissues and lymphomas can erode into muscle planes, the most common cancer of the soft parts is a collection of malignant tumors referred to as soft-tissue sarcoma. Soft-tissue sarcomas occur at any age, although the majority are seen in patients over the age of forty years. Half of the soft-tissue sarcomas occurring in children are rhabdomyosarcomas. Young adults are more likely to be diagnosed with synovial sarcomas and epithelioid sarcomas than with other types of soft-tissue sarcomas. Twice as many soft-tissue sarcomas occur in the lower extremities than occur in the upper extremities, with 40% and 20% of all soft-tissue sarcomas occurring in the lower and upper limbs, respectively
1 . Thirty percent of soft-tissue sarcomas are found in the trunk and pelvis, while 10% occur in the head and neck region.
Probably the most dangerous clinical fallacy regarding soft-tissue masses is that there is no need for concern unless a mass is painful. To the contrary, most patients with soft-tissue sarcoma present with a painless lump, just as do many with a benign soft-tissue tumor. Only very occasionally do soft-tissue sarcomas cause symptoms other than the mere presence of a lump or bump. When symptoms do occur, they are usually related to the size of the tumor, with larger masses causing local discomfort due to pressure on surrounding structures. Occasionally, soft-tissue masses may be associated with distally referred neurogenic symptoms of pain, paresthesias, or focal neurological deficits, but these findings may be caused by both large soft-tissue sarcomas and smaller benign peripheral nerve-sheath tumors.
Another common diagnostic fallacy regarding patients with soft-tissue sarcomas is that they appear ill, as do patients with nonmusculoskeletal disseminated malignant tumors. However, while questions regarding fevers, chills, night sweats, unintentional weight loss, decrease in energy level and appetite, lymphadenopathy, cough, hemoptysis, hematuria, and change in bowel or bladder habits should be asked of any patient with a suspected malignant tumor, patients with a soft-tissue sarcoma rarely have any of these systemic symptoms. Even patients with a metastatic lesion rarely have systemic symptoms. Hence, because a lack of symptoms does not mean that a mass is not malignant, a high index of suspicion for the presence of a soft-tissue sarcoma must be maintained. An affirmative answer to any question regarding constitutional symptoms from a patient with a soft-tissue mass should raise the possibility of disseminated metastatic rhabdomyosarcoma if the patient is less than fifteen years of age or the possibility of either a disseminated lymphoma or metastatic carcinoma to soft tissue if the patient is older. Unlike bone tumors, which usually have specific radiographic findings that can predict malignant or aggressive behavior, there is no reliable prebiopsy test for soft-tissue sarcomas.
Despite numerous overlapping clinical features between benign and malignant soft-tissue masses, specific physical findings help to determine to a large extent the likelihood that a tumor is malignant. Key distinguishing features are size and depth. Tumors that are either >5 cm
or deep to the fascia have the highest likelihood of being a soft-tissue sarcoma. Conversely, the vast majority of soft-tissue masses that are superficial
and <5 cm are benign. In adults, most of these small superficial masses are lipomas. In children, most small superficial soft-tissue masses are hemangiomas. However, not all small superficial masses are benign, and one-third of soft-tissue sarcomas present as small superficial masses
2 .
Some soft-tissue masses present with clinical features suggestive of a specific diagnosis. Abscesses are superficial masses that are characteristically red, rapidly enlarging, swollen, warm, and quite tender. Synovial cysts and para-articular masses are common in both adults and children. These transilluminate light if they are superficial in location. A history of fluctuation in size independent of activity is also highly suggestive of a synovial cyst. Another common benign tumor that fluctuates in size, typically with activity, is an intramuscular hemangioma. Intramuscular hemangiomas typically become engorged with blood during exercise and may cause some discomfort; with rest, the swelling and discomfort typically lessen or completely abate. Each of the most common benign soft-tissue masses has a characteristic feel on physical examination: an abscess is fluctuant, a lipoma is soft, a hemangioma is compressible, and a synovial cyst is tense but indentable with digital pressure.
Hematomas are a common clinical diagnosis but one that should be made only with the utmost caution and on the basis of the narrowest of diagnostic criteria. The clinical diagnosis of hematoma first requires a clear history of direct trauma to the region, therapeutic anticoagulation, or a clotting deficiency. The key feature on physical examination, which should be sought before this clinical diagnosis is made, is ecchymosis. Subcutaneous ecchymosis is nearly always evident with traumatic hematomas because the blood dissects along fascial planes, extending to the subcutaneous tissue. Contained bleeding may occur within tumors as well, sometimes resulting in a rapid increase in the size of the mass and radiographic features suggestive of blood products. However, blood products or bleeding alone does not make a hematoma. Bleeding within a tumor is constrained by the tumor pseudocapsule and hence does not extend along fascial planes. Hematoma without ecchymosis should be considered to be a tumor until proven otherwise (
Figs. 1-A, 1-B, and 1-C ).
When a history is obtained from a patient with a soft-tissue mass, all of the salient features described above should be noted. In particular, the timing, growth, and nature of discovery of the soft-tissue mass are important. A long-standing non-enlarging soft-tissue mass is less likely to be a sarcoma than is one that was noticed relatively recently and was noted to have recently enlarged. Fluctuation in size usually suggests a benign process, such as a synovial cyst or a hemangioma. Neurogenic symptoms associated with a small soft-tissue mass on the flexor surface of the extremity usually indicate a benign peripheral nerve-sheath tumor. The absence of pain has little bearing on the differentiation between benign and malignant soft-tissue masses.
A comprehensive medical history should include details of any prior benign or malignant tumor, soft-tissue or otherwise, that had been removed. Lung and renal carcinomas have a propensity, compared with other primary carcinomas, for soft-tissue metastases. Lymphomas and multiple myeloma also involve the soft tissue with some regularity. Certain sarcomas, including liposarcomas, angiosarcomas, leiomyosarcomas, mesenchymal chondrosarcomas, and rhabdomyosarcomas, have a propensity for multifocality. Patients with multiple lipomas may have a higher prevalence of liposarcoma. Patients should be asked if they have any of the conditions known to be associated with the development of soft-tissue sarcomas, including type-I (peripheral) neurofibromatosis, Gardner syndrome (familial polyposis coli and desmoid tumors), and a history of local irradiation. Underlying medical conditions may point to a specific diagnosis, such as a synovial cyst or exuberant pannus in a patient with rheumatoid arthritis and skeletal muscle necrosis in a patient with diabetes. A history of gout should be sought, for consideration of a gouty tophus as an explanation, when a patient has a juxta-articular soft-tissue mass in a lower extremity.
When recording the family history, the examiner should seek evidence of Maffucci syndrome, von Recklinghausen disease, and Gardner syndrome. The review of systems should include questions about constitutional symptoms, although they are rarely present even in patients with metastatic soft-tissue sarcoma. Occasionally, the diagnosis of a malignant tumor can lead to the recognition of a genetic disorder, such as neurofibromatosis in a patient with a new neurosarcoma.
Physical examination of a patient with a soft-tissue mass should include a complete general examination to uncover evidence of other masses, malignant skin lesions, other signs of malignancy or metastatic disease, and systemic signs of diseases that may result in soft-tissue masses, such as lymphadenitis in a patient who handles outdoor cats. Usually, the patient should wear a gown for the examination, or at least both extremities should be fully exposed so that subtle asymmetry can be appreciated. A thorough examination of the skin should reveal any
café-au-lait spots or axillary freckling possibly indicative of neurofibromatosis. Associated lymphedema in the affected extremity should increase suspicion for lymphangiosarcoma. A careful examination of the lymph nodes should be done, although such metastases are rare with sarcomas. Extensive lymphadenopathy is usually more suggestive of a lymphoma. Soft-tissue sarcomas with a propensity for lymphoid spread include rhabdomyosarcoma, angiosarcoma, clear-cell sarcoma, epithelioid sarcoma, and synovial sarcoma. A neurovascular examination of the extremity distal to the mass should be undertaken, and the findings should be compared with those on the contralateral side. For certain soft-tissue tumors, the anatomic site is highly suggestive of a specific diagnosis, such as elastofibroma in the subscapular region, plantar fibromatosis in the plantar medial aspect of the foot, cat-scratch disease in the axillary or epitrochlear nodal region, and a ganglion cyst on the dorsum of the hand or around the knee. However, the presence of a mass in one of those areas does not in and of itself ensure that the common site-specific diagnosis is correct.
The mass should be examined to determine its size, depth, contour, texture, mobility, warmth, color, vascularity, and transillumination. The importance of size and depth in distinguishing a soft-tissue mass that is probably benign from one that is probably malignant was noted previously. Specific textures include the fatty feel of a lipoma, the compressible nature of a hemangioma, and the fluctuance of an abscess. Mobility in the transverse plane without proximal-to-distal mobility favors a diagnosis of peripheral nerve-sheath tumor. Warmth may indicate an infection, a desmoid tumor, or a malignant tumor. Erythema favors a diagnosis of infection. Vascular ectasia in the overlying skin suggests an underlying hemangioma (
Fig. 2 ). An audible thrill or palpable bruit may indicate a vascular aneurysm or a vascular malformation with an arteriovenous shunt. Transillumination is evidence of the cystic nature of a mass and is most commonly seen with synovial cysts. Ulceration of the overlying skin may herald an epithelioid sarcoma.
On the basis of these many pieces of evidence, the clinician will form an initial impression regarding whether the mass is probably benign, possibly malignant, or probably malignant. A specific diagnosis may be suggested. This initial impression will guide the subsequent steps in the evaluation and management of a patient with a soft-tissue mass.
Very little useful information is gained from a laboratory evaluation of a patient with a soft-tissue mass. Some infections may result in an elevated white blood-cell count, erythrocyte sedimentation rate, and/or C-reactive protein level, but these findings are nonspecific. An elevated level of lactate dehydrogenase is frequently seen in patients with lymphoma, and the degree of elevation is a crude measure of the disease load. When there is a suspicion of gout, serum uric acid levels should be measured.
The initial radiographic evaluation of a soft-tissue mass should start with plain radiographs
3,4 , which, in most instances, reveal only a nonspecific mass effect. Radiographs of intramuscular lipomas, however, usually demonstrate the fatty nature of the mass as a dark area within the slightly more radiopaque muscle shadow. Calcification within a soft-tissue mass may take many forms. Phleboliths have a characteristic appearance. They are smooth, round radiodense areas and are sometimes seen within vascular malformations or hemangiomas (
Fig. 3 ). A peripheral rim of radiodensity that develops within a contused muscle within a few weeks after direct trauma and matures over time is a classic feature of myositis ossificans (
Fig. 4 ). A cartilaginous pattern of mineralization may be seen in mesenchymal chondrosarcoma. In contrast, a central or disorganized pattern of dystrophic mineralization may be seen within a soft-tissue sarcoma. While nearly any soft-tissue sarcoma can cause such mineralization, this finding is seen most commonly in synovial sarcoma (
Fig. 5 ).
Involvement of bone by both benign and malignant soft-tissue masses may be appreciated on plain radiographs. This involvement may take the form of osseous erosion, periosteal reaction, or cortical hyperostosis. Bone erosion is unusual for both benign and malignant soft-tissue masses. Possibly because of the tight confines of the digits, however, giant-cell tumors of the tendon sheath have been reported to frequently cause bone erosions (
Fig. 6 ). Cortical hyperostosis, or thickening, may occur in the presence of a long-standing soft-tissue mass closely juxtaposed to bone, such as an intramuscular hemangioma.
Ultrasound is a useful tool to confirm the clinical impression of a synovial cyst. Complete loss of echogenicity is essentially diagnostic of a synovial cyst. However, the presence of echoes (snow or cloudiness) within the mass or a radiologist's interpretation of a mass as being a "complicated cyst" should be viewed with some skepticism, as these findings may also be seen with a sarcoma that has a cystic component. Ultrasound also may be used as a means to periodically evaluate a small mass that is being followed without excision. A baseline sonogram can be compared with subsequent ultrasound studies if there is a clinical suspicion of tumor enlargement. An increase in growth can be accurately assessed by examining the change on the ultrasound studies.
Typically, computerized tomography is utilized only in specific situations. It is particularly helpful in identifying and characterizing mineralization within soft-tissue masses, such as those suspected to represent myositis ossificans (
Fig. 4 ). Cortical involvement may also be best evaluated with computerized tomography. Otherwise, computerized tomography is generally reserved for staging evaluation for potential lung, abdomen, and/or pelvic metastases from soft-tissue sarcomas, lymphomas, and metastatic carcinomas as well as for use as a tool to facilitate localization of a tumor for a percutaneous needle biopsy (computerized tomography-guided needle biopsy).
The most sensitive and specific radiographic study for imaging of soft-tissue masses is magnetic resonance imaging
5 . Its use is indicated whenever a diagnosis of soft-tissue sarcoma cannot be excluded on the basis of the findings of the clinical evaluation. It is also often indicated for preoperative planning prior to excision of benign soft-tissue masses. Magnetic resonance imaging has the well-established advantages of excellent differentiation of various soft-tissue types, adequate bone-marrow imaging, the capability for multiplanar imaging, and the option of including enhancement and vascular studies. Unfortunately, relatively few specific diagnoses of soft-tissue masses can be established on the basis of magnetic resonance imaging. The five different specific diagnoses that can be made with some consistency are based, in large part, on the identification of a specific tissue type, inherent in those tumors, that has characteristic features on magnetic resonance imaging (
Table I ). A ganglion or synovial cyst (
Figs. 7-A and 7-B ) and lymphangioma exhibit homogeneous fluid signal characteristics; a lipoma exhibits characteristics of fat (
Fig. 8 ); pigmented villonodular synovitis, those of hemosiderin (
Figs. 9-A, 9-B, and 9-C ); and fibromatosis (desmoid tumor), those of fibrous tissue (
Figs. 10-A and 10-B ). Intramuscular hemangioma, another process that in many cases can be diagnosed with some confidence with magnetic resonance imaging, is characterized by serpiginous intramuscular markings with high-intensity signal on T2-weighted images, infiltrative borders frequently with minimal mass effect, and a variable amount of fat (
Figs. 11-A and 11-B ). Unfortunately, soft-tissue sarcoma is not one of the specific diagnoses that can be established with certainty on the basis of the findings of magnetic resonance imaging. Most soft-tissue sarcomas appear nonhomogeneous with low-intensity T1 signal and high-intensity T2 signal surrounded by some perilesional edema, but this is a nonspecific appearance and is not observed in all soft-tissue sarcomas (
Figs. 12-A through 12-D ).
The role of isotope scanning continues to evolve. Historically, the only role was for technetium-99 scans in the staging of suspected soft-tissue sarcomas. Given the rarity of bone metastasis in the absence of the more common lung metastasis, the role of even this basic study has been questioned. Currently, positron emission tomography (PET) scans (F-18 fluorodeoxyglucose imaging) are used in some centers for the evaluation of recurrent soft-tissue sarcomas and distant metastases, but their role has not yet been established
6-9 .
Biopsy of a soft-tissue mass is indicated when clinical and radiographic evaluation does not yield a conclusive diagnosis or when the soft-tissue mass must be removed. However, biopsy is a double-edged sword
10,11 . If done inappropriately, it may result in diagnostic errors, inappropriate alteration of treatment, unnecessary amputation, and an even worse prognosis
12-14 (
Figs. 1-A, 1-B, and 1-C ). Hence, all biopsy principles should be considered carefully before this crucial step is undertaken. Two criteria should be met before proceeding. First, the pathologist should have experience in musculoskeletal pathology. Second, the surgeon should have experience in dealing with all of the possible diagnoses considered in the prebiopsy differential diagnosis. If either of these criteria is not met, the patient should be referred to a center where patients with musculoskeletal sarcoma are routinely diagnosed and treated. If a patient is referred to such a center early, before inappropriate manipulation of the tumor and surrounding tissues has been performed, he or she will have the best chance for receiving limb-sparing surgery, local control of the tumor, and possibly a cure.
Errors related to the biopsy of soft-tissue masses continue to occur. Two of the most common take place when the lesion is assumed to be benign and either is "shelled out" inappropriately or ignored without follow-up (
Figs. 12-A through 12-D ). Some masses are excised without adequate preoperative imaging because of the expense of the tests and the rationale that the tumor "needs to come out anyway" without any regard for the specific diagnosis or how that might affect the ultimate surgical resection if the lesion is malignant. Even needle biopsy prior to adequate imaging can cause problems if it is inappropriately performed. Interpretation of magnetic resonance images made following needle biopsy is complicated by procedural edema that creates confusion regarding the characteristics and extent of the tumor. The fact that a tumor is seen to be "well encapsulated" on a magnetic resonance image or is easily shelled out at the time of an open biopsy does not rule out the diagnosis of sarcoma (
Figs. 13-A, 13-B, adn 13-C ). These characteristics should not convince the surgeon that the mass is benign. Simultaneous surgery such as arthroscopy or excision of other lumps potentially contaminates the areas unnecessarily if one of the lumps turns out to be malignant. Arthroscopy performed through a contaminated sarcoma bed has the potential to introduce tumor cells into the joint. This complicates treatment and often leads to an amputation. Transverse incisions are inappropriately used because of their often superior cosmetic results. If a more extensive resection is required, a complex excision and reconstruction is often necessary because the biopsy incision and all tissue previously exposed must be excised at the time of the definitive surgery. One of the most damaging errors is embarking on a course of treatment without a well-established diagnosis. This most commonly happens when the lesion is presumed be a hematoma; these lesions are occasionally drained, irrigated, or evacuated without a biopsy. This produces wide contamination of surrounding areas by the eventually discovered underlying soft-tissue sarcoma (
Figs. 1-A, 1-B, adn 1-C ). The aspirated fluid from any bloody soft-tissue mass can be sent to the pathologist for analysis of malignant cells prior to any intervention. This simple step should prevent the above-described mistake in a patient with an expanding "hematoma" without major trauma to the area.
Biopsy should be done expeditiously but not until all indicated imaging studies have been performed; the case has been reviewed with the radiologist and pathologist; and, if necessary, an orthopaedic oncologist has been consulted. The most common types of biopsies utilized for soft-tissue masses are fine-needle aspiration, core-needle, and open biopsies
15-19 . Fine-needle aspiration is typically performed by interventional radiologists or pathologists, has the advantage of minimal morbidity for the patient, and may be performed in conjunction with computerized tomography for enhanced visualization. One disadvantage is that the person performing the fine-needle biopsy frequently has little understanding of the surgical treatment of soft-tissue sarcoma. Therefore, he or she may not appreciate the principles of biopsy tract placement to allow ease of excision of the tract at the time of the definitive surgery. Another disadvantage of fine-needle biopsy is the relative paucity of procured tissue, which makes pathological interpretation challenging. The pathologist who interprets a specimen obtained with a fine-needle biopsy must have experience with this method of biopsy. Hence, at the very least, fine-needle biopsy should be done only in centers where the pathologists are experienced in the interpretation of the findings of fine-needle biopsy performed for musculoskeletal tumors and where there is close communication between the orthopaedic surgeon and the physician performing the biopsy. A negative or nondiagnostic finding on fine-needle biopsy cannot be relied on to exclude the diagnosis of malignant tumor; it means only that additional tissue should be obtained.
The most commonly employed technique for biopsy of soft-tissue masses is the core biopsy. Usually, this is accomplished with a cutting-needle biopsy system in the physician's office or in a radiology suite with the patient under local anesthesia. Placement of the needle should be carefully planned; it should be in the planned line of excision of the mass, avoiding unnecessary contamination of uninvolved structures. An adequate specimen can be obtained in a large percentage of cases without the logistical complications and expense of a formal open biopsy in the operating room. Still, if only nondiagnostic tissue is obtained, the mass should not be assumed to be benign; additional biopsy material should be obtained.
In some cases, an open biopsy is indicated and, in these situations, an additional set of technical considerations applies. First, adequate hemostasis must be obtained and maintained. A tourniquet may be used during the biopsy, but exsanguination of the limb should be accomplished by gravity alone. In order for the biopsy tract to be excised easily with the definitive surgery, it must be placed longitudinally or parallel to the muscle beneath it, as in the shoulder and hip regions. Transverse incisions in the extremities should be avoided. The biopsy tract should proceed within the involved compartment without unnecessary contamination of the joint, compartmental septa, major vessels, or nerves. The specimen should be obtained without crushing or cauterization, and it should be delivered immediately to the pathologist fresh on a moistened Telfa pad for preparation of a frozen section while the patient is still on the operating table. Preparation of a frozen section is advisable in order to determine if the specimen is viable and adequate in quantity. When these questions are answered in the affirmative by the pathologist, the goals of the biopsy have been accomplished. While the goal of the examination of the frozen section does not need to be a definitive diagnosis, usually a definitive diagnosis can be made. Often the definitive surgery can be done immediately on the basis of the diagnosis determined by examination of the frozen section. This saves the patient an additional separate surgical procedure. Hemostasis should be obtained after releasing the tourniquet prior to wound closure to avoid contamination by dissection of bleeding elsewhere in the extremity. If a drain is necessary, it should be placed so that the exit site is close to and in line with the end of the incision.
Treatment of soft-tissue masses is based on their size and location and is influenced by other important information gleaned from the clinical and radiographic evaluations
20 . In general, however, the surgical options differ depending on whether the tumor is >5 cm and whether it is deep to, or involves, the fascia. With these two pieces of information, all tumors can be divided into four categories: small superficial, large superficial, small deep, and large deep. Similarly, there are four categories of tumor excision: intralesional, marginal, wide, and radical
21 . Intralesional excision is defined as the piecemeal removal of the tumor. This can be appropriate for synovitis, synovial cysts, pigmented villonodular synovitis, and synovial chondromatosis. Marginal excision is defined as complete removal of the tumor with the pseudocapsule left intact. Marginal excision is appropriate for noninfiltrative benign soft-tissue tumors. Desmoid tumors are benign, but they infiltrate the adjacent tissue and thus require more than a marginal excision. Wide resection is defined as removal of the tumor with a cuff of normal tissue in all planes without exposing the pseudocapsule. It is the optimal surgical procedure for most soft-tissue sarcomas and desmoid tumors. A radical resection involves removal of the entire muscle compartment, or compartments, involved by the tumor. This type of surgery often requires an amputation since most sarcomas are extracompartmental. A radical resection is used for some intracompartmental soft-tissue sarcomas when a wide resection would be associated with as much morbidity as a complete compartmental resection, when there have been many local recurrences of the soft-tissue sarcoma, or when the sarcoma has been neglected.
Small superficial tumors are <5 cm, are easily palpable beneath the skin, and do not become more firm with muscular contraction. The vast majority of these masses in adults are lipomas. However, melanoma is a concern when a mass is found in this superficial location, so skin changes should be evaluated. If a melanoma is suspected, oncologic referral is appropriate. If there is a history of carcinoma, the possibility of metastatic carcinoma should be considered, and incisional biopsy is appropriate. If the mass is inflamed, painful, fluctuant, and suggestive of an abscess, it should be aspirated. Aspiration is also useful for a transilluminating mass that is suspected of being a synovial cyst. If the small superficial mass does not fall into any of these categories, it is most likely benign and should be either observed closely for change or excised. Some surgeons believe that all such masses should be excised. If excisional biopsy is chosen, a marginal excision can be done, but all other biopsy principles should be adhered to and the deep fascia should be left undisturbed. The entire specimen should be submitted for histological evaluation of permanent sections
22,23 .
Because one-third of soft-tissue sarcomas occur within the subcutaneous tissue, occasionally the pathology report on an otherwise benign-appearing small superficial excised mass will reveal an unsuspected soft-tissue sarcoma. With this scenario, the patient should be referred to an orthopaedic oncologist, who will typically perform a wide re-excision of the operative field. The prognosis for these patients is quite good, with a five-year survival rate of >90%
24 .
Large superficial soft-tissue masses are >5 cm, are easily palpable beneath the skin, and do not become more firm with muscular contraction. These tumors almost always warrant evaluation on plain radiographs and with magnetic resonance imaging. Many will turn out to be benign tumors, such as lipomas or synovial cysts. If the magnetic resonance imaging suggests a benign lipoma that is identical to normal fat on all images and is without gadolinium enhancement, the mass is a lipoma and can be excised or ignored
25 . If the magnetic resonance imaging suggests a synovial cyst, an aspiration can be done to confirm the diagnosis. If a specific diagnosis cannot be made on the basis of these imaging studies, the mass may be a soft-tissue sarcoma. An incisional biopsy should be performed, preferably by an oncologic surgeon.
A small deep tumor is <5 cm and is located deep to the fascia; consequently, it becomes more firm with muscular contraction. Specific findings on physical examination may point to specific diagnoses: for example, the Tinel sign suggests a peripheral nerve-sheath tumor; tenderness to palpation, deep infection; and a bruit on auscultation, a vascular lesion or aneurysm. Small deep tumors should be evaluated on plain radiographs and with magnetic resonance imaging. If gadolinium-enhanced magnetic resonance imaging suggests a nonenhancing lipoma, the tumor may be excised marginally with care taken to preserve any nerves in close proximity. If the imaging suggests a benign peripheral nerve-sheath tumor such as a schwannoma, it may be marginally excised as well, with care taken not to damage a major nerve. A nonspecific magnetic resonance image may represent a soft-tissue sarcoma. In that case, referral to an oncologic surgeon is appropriate prior to biopsy. The outcome for patients with a small deep soft-tissue sarcoma is still quite good, with a five-year disease-free survival rate of 82%
24 .
A large deep tumor is >5 cm and is located deep to the fascia. Appropriate initial evaluation includes a comprehensive physical examination, plain radiographs, and magnetic resonance imaging. Evidence of lymphadenopathy most commonly suggests a lymphoma, although occasionally a soft-tissue sarcoma can metastasize to lymph nodes. In either event, referral to a musculoskeletal oncologist is recommended because of the high likelihood of malignancy. Similarly, the absence of a specific benign diagnosis, such as lipoma, based on magnetic resonance imaging also warrants referral to a musculoskeletal oncologist. Even the presence of predominantly homogeneous fatty signal characteristics on magnetic resonance imaging may not ensure the diagnosis of a benign intramuscular lipoma, since similar, if not identical, signal characteristics may be seen with low-grade fatty malignant tumors, variously referred to as
atypical lipomas or
low-grade lipoma-like liposarcomas . Deep, large fatty masses, even when benign, may be difficult to excise because of their intimate association with, and occasional encasement of, neurovascular structures, particularly when they are in an intermuscular rather than an intramuscular position. The primary treatment for a large deep soft-tissue sarcoma is wide surgical excision. Hence, the placement of the biopsy is very important with this group of tumors. Irradiation is used as an adjuvant to surgery. When the surgical margins will be or were insufficient without an amputation, irradiation reduces the risk of local recurrence. Chemotherapy, while controversial, can be considered for patients with a high-grade, large, deep soft-tissue sarcoma
25-44 . The five-year survival rate after appropriate treatment is 82% to 98% for low-grade large, deep soft-tissue sarcomas, 80% for intermediate-grade tumors, and 52% to 60% for high-grade tumors
24,45 .
In summary, soft-tissue tumors are a common problem. Every orthopaedist should be familiar with the front-line evaluation of these tumors in order to distinguish those that require referral to a musculoskeletal oncologist from those that do not. Size and depth are the two most important factors on which triage decisions should be based. When biopsy is to be performed, careful attention to detail with respect to multidisciplinary coordination beforehand, cautious execution of the procedure to minimize complications, and expedient follow-up and referral to a musculoskeletal oncologist when appropriate, are essential. Only in this fashion will appropriate patient care be achieved.
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