Fine-Needle Aspiration Biopsy of Sarcomas and Related Tumors
Fine-Needle Aspiration Biopsy of Sarcomas and Related Tumors
Background: Largely due to a lack of experience, familiarity, and/or confidence, few centers rely on simple fine-needle aspiration biopsy (FNAB) for the diagnosis of sarcomas and related tumors.
Methods: The authors have reviewed their own experience in more than 200 cases of FNAB of bone and soft-tissue tumors, as well as cases reported in the literature.
Results: FNAB has proven to be accurate and useful in 8 consecutive years of clinical experience. No serious complications have occurred.
Conclusions: FNAB is recommended as an integral part of the initial evaluation of amenable orthopaedic tumors, including sarcomas, especially in cases with classic clinical and radiographic findings.
Fine-needle aspiration biopsy (FNAB) of previously undiagnosed masses or suspected orthopaedic tumors has multiple advantages compared to open biopsy. It is quick, inexpensive, and minimally invasive, and it can often be performed on the day of the initial office visit. It has been shown to establish the diagnosis of osteosarcomas at less than one fourth the cost of open biopsy. FNAB can generally be performed without any anesthesia, it causes minimal to no discomfort, and it is well tolerated by patients. FNAB is performed using a 23- or 25-gauge needle. When offered a choice of open vs needle biopsy, most patients prefer the simpler needle biopsy. Diagnostic aspiration biopsies obviate the need for open biopsies.
FNAB is an integral component of an overall team approach to the diagnosis and treatment of bone and soft-tissue tumors. Our team includes an orthopaedic oncologist, a medical oncologist, radiologists, and pathologists. The pathologists must be skillful in the cytopathologic interpretation of orthopaedic tumor aspirates. Due in part to both the shortage of cytopathologists with experience in orthopaedic tumors and the lack of exposure of orthopaedic oncologists to the FNAB procedure, the technique is utilized at only a few orthopaedic tumor centers throughout the United States. However, its use is increasing as experience is gained with the technique. It allows operating room time to be more appropriately utilized for tumor resections rather than unnecessary open biopsy procedures. FNAB is perhaps most accepted for the diagnosis of locally recurrent and metastatic lesions in which a diagnosis of sarcoma has been previously established. It is gaining increasing acceptance for the diagnosis of primary tumors of bone and soft tissues, both benign and malignant.
We initially began utilizing FNAB on tumors that had a classic radiographic appearance such as high-grade osteosarcoma. Its role was that of a confirmatory test. We have expanded our use of FNAB to include most previously undiagnosed orthopaedic masses and tumors. FNAB is most successfully utilized when it is simply confirming the clinicoradiographic diagnosis in a patient whose tumor has classic presentation. For example, a patient in the 20- to 40-year-old age group with a distal femoral or proximal tibial lytic, eccentric, geographic, subchondral epiphyseal lesion almost certainly has a giant cell tumor (Fig 1A). FNAB is excellent at confirming the diagnosis of giant cell tumor of bone (Fig 1B). Appropriate laboratory tests may be required to rule out associated hyperparathyroidism, but FNAB provides great reliability in diagnosing giant cell tumors. This allows surgery to proceed expeditiously with a confirmed preoperative diagnosis and avoids the need to wait for the pathologists to process the frozen section intraoperatively. Alternatively, should an osteo-sarcoma be diagnosed at FNAB, then the appropriate systemic evaluation and chemotherapy can be initiated quickly, without having to schedule and perform an open procedure.
(Enlarge Image)
AP and lateral radiograph of a classic giant cell tumor. (Used by permission of W. G. Ward, MD.)
(Enlarge Image)
FNAB aspirate of giant cell tumor. (Used by permission of W. G. Ward, MD.)
FNAB is successful in the diagnosis of bone malignancies. Previous studies have shown it to be highly accurate in diagnosing osteosarcoma, myeloma, and Ewing's sarcoma as well as other bony sarcomas. In our experience, FNAB can correctly identify bony sarcomas in 93% of cases in which adequate aspiration specimens are obtained. Histogenetic subtyping can be achieved in approximately 82% of these same cases. Few centers would be willing to treat or consider treating a patient with a high-grade osteosarcoma, even with a classic radiographic and clinical presentation, without histologic confirmation. FNAB is well suited to provide histologic confirmatory tests in such situations, allowing chemotherapy to be initiated within 2-3 days of the initial office visit. Reliance on FNAB for diagnosis avoids an open biopsy with its potential systemic seeding, local tumor spread, and tissue tumor contamination. Although complications from local tumor spread are avoidable with proper technique in many open biopsies, some tumor spread and tissue contamination will of necessity occur in even the most skillful hands. The hazards of open biopsy have been well documented, especially when performed with suboptimal technique.
FNAB is also useful in the management and evaluation of both benign and malignant soft-tissue tumors. Inappropriate or incomplete surgical excision of presumed benign lesions ultimately found to be malignant may be avoided by the judicious use of FNAB. The management of benign lesions can be simplified following a diagnostic FNAB. For example, in several cases, unsuspected large gouty tophi that were mimicking sarcomas were readily diagnosed by FNAB. Similarly, unsuspected abscesses can be identified with FNAB, obviating the need for a more expensive workup and allowing initiation of appropriate treatment. The diagnosis of certain benign lesions, such as ganglions and popliteal cysts, can be cytologically confirmed. When the FNAB findings are considered in conjunction with classic radiographic findings, many benign entities can safely be clinically observed. The physician gains a greater sense of confidence that a more worrisome lesion, such as a low-grade myxoid sarcoma, has not been overlooked following a diagnostic FNAB. However, an FNAB that is "negative for malignancy" or that "contains no malignant cells" does not absolutely confirm the absence of malignancy. It simply means that no identifiable malignant cells were aspirated and expelled onto the glass slide. This could be due to nonrepresentative sampling, to the needle having missed the lesion altogether, or to the absence of a malignant entity. Therefore, a "negative" FNAB should be accepted only as one component of an overall diagnostic picture. Particularly with deeper lesions, imagingguided FNAB can avoid a false-negative finding due to the needle missing the lesion. If the cytologic findings and interpretations are not consistent with the clinical and radiographic findings and a malignancy is suspected, then open biopsy or core needle biopsy is indicated.
Malignant soft-tissue lesions are likely to be appropriately identified with FNAB. They often can be differentiated into histologic subtypes such as myxoid liposarcoma, extraskeletal mesenchymal chondrosarcoma, and malignant fibrous histiocytoma, but many can be identified only as a pleomorphic sarcoma. This may not be problematic because such an interpretation essentially equates to high-grade sarcoma, which may be sufficiently diagnostic for current treatment regimens. In the setting of an adequate FNAB aspiration specimen, approximately 86% of soft-tissue sarcomas can be correctly identified as sarcomas by FNAB, and approximately 54% can be properly classified into their histologic subtype.
The success of FNAB is somewhat dependent on the diagnostic specificity required by the individual oncology team. At our institution, we treat large, high-grade soft-tissue sarcomas with preoperative chemotherapy followed by wide resection, additional chemotherapy, and ultimately radiation therapy. The postoperative chemotherapy regimen is partly dependent on the tumor's response to the preoperative chemotherapy. This is determined by both the histologic evaluation of the resected specimen and the use of other clinical parameters of tumor response such as shrinkage or necrosis detected clinically and documented by magnetic resonance imaging (MRI).
Our general approach to low-grade malignant lesions is to do a wide resection without any preoperative therapy. It could be argued that at our institution, essentially all malignant orthopaedic soft-tissue tumors are ultimately treated with wide resections. Thus, although the FNAB diagnosis of malignancy is established preoperatively, most soft-tissue tumors will warrant a wide resection. However, the use of FNAB allows selection of patients with high-grade malignancies for preoperative chemotherapy.
FNAB is generally not utilized to differentiate lipoma from low-grade lipoma-like liposarcoma. This differentiation can be difficult on standard histology. Unless the lesion dedifferentiates, the primary clinical concern with well-differentiated lipoma-like liposarcoma is only local recurrence. We treat both lipomatous lesions (lipoma and lipoma-like liposarcoma) essentially the same, with an extracapsular wide resection. Since extensive sampling is often required to differentiate between the two entities and since both are best treated with complete resection, we wait on final pathology to differentiate these lesions. We have been able to correctly predict the pathologic diagnosis preoperatively in most cases by careful analysis of the MRI or computed tomography (CT) images. If there is internal signal streaking or inhomogeneity, lipoma-like liposarcoma is suspected. If a pure homogeneous, fatappearing image is present, lipoma is suspected, and we resect less margin tissue at surgery, opting for a true capsular resection. Thus far, we have not encountered a problem with this approach.
Background: Largely due to a lack of experience, familiarity, and/or confidence, few centers rely on simple fine-needle aspiration biopsy (FNAB) for the diagnosis of sarcomas and related tumors.
Methods: The authors have reviewed their own experience in more than 200 cases of FNAB of bone and soft-tissue tumors, as well as cases reported in the literature.
Results: FNAB has proven to be accurate and useful in 8 consecutive years of clinical experience. No serious complications have occurred.
Conclusions: FNAB is recommended as an integral part of the initial evaluation of amenable orthopaedic tumors, including sarcomas, especially in cases with classic clinical and radiographic findings.
Fine-needle aspiration biopsy (FNAB) of previously undiagnosed masses or suspected orthopaedic tumors has multiple advantages compared to open biopsy. It is quick, inexpensive, and minimally invasive, and it can often be performed on the day of the initial office visit. It has been shown to establish the diagnosis of osteosarcomas at less than one fourth the cost of open biopsy. FNAB can generally be performed without any anesthesia, it causes minimal to no discomfort, and it is well tolerated by patients. FNAB is performed using a 23- or 25-gauge needle. When offered a choice of open vs needle biopsy, most patients prefer the simpler needle biopsy. Diagnostic aspiration biopsies obviate the need for open biopsies.
FNAB is an integral component of an overall team approach to the diagnosis and treatment of bone and soft-tissue tumors. Our team includes an orthopaedic oncologist, a medical oncologist, radiologists, and pathologists. The pathologists must be skillful in the cytopathologic interpretation of orthopaedic tumor aspirates. Due in part to both the shortage of cytopathologists with experience in orthopaedic tumors and the lack of exposure of orthopaedic oncologists to the FNAB procedure, the technique is utilized at only a few orthopaedic tumor centers throughout the United States. However, its use is increasing as experience is gained with the technique. It allows operating room time to be more appropriately utilized for tumor resections rather than unnecessary open biopsy procedures. FNAB is perhaps most accepted for the diagnosis of locally recurrent and metastatic lesions in which a diagnosis of sarcoma has been previously established. It is gaining increasing acceptance for the diagnosis of primary tumors of bone and soft tissues, both benign and malignant.
We initially began utilizing FNAB on tumors that had a classic radiographic appearance such as high-grade osteosarcoma. Its role was that of a confirmatory test. We have expanded our use of FNAB to include most previously undiagnosed orthopaedic masses and tumors. FNAB is most successfully utilized when it is simply confirming the clinicoradiographic diagnosis in a patient whose tumor has classic presentation. For example, a patient in the 20- to 40-year-old age group with a distal femoral or proximal tibial lytic, eccentric, geographic, subchondral epiphyseal lesion almost certainly has a giant cell tumor (Fig 1A). FNAB is excellent at confirming the diagnosis of giant cell tumor of bone (Fig 1B). Appropriate laboratory tests may be required to rule out associated hyperparathyroidism, but FNAB provides great reliability in diagnosing giant cell tumors. This allows surgery to proceed expeditiously with a confirmed preoperative diagnosis and avoids the need to wait for the pathologists to process the frozen section intraoperatively. Alternatively, should an osteo-sarcoma be diagnosed at FNAB, then the appropriate systemic evaluation and chemotherapy can be initiated quickly, without having to schedule and perform an open procedure.
(Enlarge Image)
AP and lateral radiograph of a classic giant cell tumor. (Used by permission of W. G. Ward, MD.)
(Enlarge Image)
FNAB aspirate of giant cell tumor. (Used by permission of W. G. Ward, MD.)
FNAB is successful in the diagnosis of bone malignancies. Previous studies have shown it to be highly accurate in diagnosing osteosarcoma, myeloma, and Ewing's sarcoma as well as other bony sarcomas. In our experience, FNAB can correctly identify bony sarcomas in 93% of cases in which adequate aspiration specimens are obtained. Histogenetic subtyping can be achieved in approximately 82% of these same cases. Few centers would be willing to treat or consider treating a patient with a high-grade osteosarcoma, even with a classic radiographic and clinical presentation, without histologic confirmation. FNAB is well suited to provide histologic confirmatory tests in such situations, allowing chemotherapy to be initiated within 2-3 days of the initial office visit. Reliance on FNAB for diagnosis avoids an open biopsy with its potential systemic seeding, local tumor spread, and tissue tumor contamination. Although complications from local tumor spread are avoidable with proper technique in many open biopsies, some tumor spread and tissue contamination will of necessity occur in even the most skillful hands. The hazards of open biopsy have been well documented, especially when performed with suboptimal technique.
FNAB is also useful in the management and evaluation of both benign and malignant soft-tissue tumors. Inappropriate or incomplete surgical excision of presumed benign lesions ultimately found to be malignant may be avoided by the judicious use of FNAB. The management of benign lesions can be simplified following a diagnostic FNAB. For example, in several cases, unsuspected large gouty tophi that were mimicking sarcomas were readily diagnosed by FNAB. Similarly, unsuspected abscesses can be identified with FNAB, obviating the need for a more expensive workup and allowing initiation of appropriate treatment. The diagnosis of certain benign lesions, such as ganglions and popliteal cysts, can be cytologically confirmed. When the FNAB findings are considered in conjunction with classic radiographic findings, many benign entities can safely be clinically observed. The physician gains a greater sense of confidence that a more worrisome lesion, such as a low-grade myxoid sarcoma, has not been overlooked following a diagnostic FNAB. However, an FNAB that is "negative for malignancy" or that "contains no malignant cells" does not absolutely confirm the absence of malignancy. It simply means that no identifiable malignant cells were aspirated and expelled onto the glass slide. This could be due to nonrepresentative sampling, to the needle having missed the lesion altogether, or to the absence of a malignant entity. Therefore, a "negative" FNAB should be accepted only as one component of an overall diagnostic picture. Particularly with deeper lesions, imagingguided FNAB can avoid a false-negative finding due to the needle missing the lesion. If the cytologic findings and interpretations are not consistent with the clinical and radiographic findings and a malignancy is suspected, then open biopsy or core needle biopsy is indicated.
Malignant soft-tissue lesions are likely to be appropriately identified with FNAB. They often can be differentiated into histologic subtypes such as myxoid liposarcoma, extraskeletal mesenchymal chondrosarcoma, and malignant fibrous histiocytoma, but many can be identified only as a pleomorphic sarcoma. This may not be problematic because such an interpretation essentially equates to high-grade sarcoma, which may be sufficiently diagnostic for current treatment regimens. In the setting of an adequate FNAB aspiration specimen, approximately 86% of soft-tissue sarcomas can be correctly identified as sarcomas by FNAB, and approximately 54% can be properly classified into their histologic subtype.
The success of FNAB is somewhat dependent on the diagnostic specificity required by the individual oncology team. At our institution, we treat large, high-grade soft-tissue sarcomas with preoperative chemotherapy followed by wide resection, additional chemotherapy, and ultimately radiation therapy. The postoperative chemotherapy regimen is partly dependent on the tumor's response to the preoperative chemotherapy. This is determined by both the histologic evaluation of the resected specimen and the use of other clinical parameters of tumor response such as shrinkage or necrosis detected clinically and documented by magnetic resonance imaging (MRI).
Our general approach to low-grade malignant lesions is to do a wide resection without any preoperative therapy. It could be argued that at our institution, essentially all malignant orthopaedic soft-tissue tumors are ultimately treated with wide resections. Thus, although the FNAB diagnosis of malignancy is established preoperatively, most soft-tissue tumors will warrant a wide resection. However, the use of FNAB allows selection of patients with high-grade malignancies for preoperative chemotherapy.
FNAB is generally not utilized to differentiate lipoma from low-grade lipoma-like liposarcoma. This differentiation can be difficult on standard histology. Unless the lesion dedifferentiates, the primary clinical concern with well-differentiated lipoma-like liposarcoma is only local recurrence. We treat both lipomatous lesions (lipoma and lipoma-like liposarcoma) essentially the same, with an extracapsular wide resection. Since extensive sampling is often required to differentiate between the two entities and since both are best treated with complete resection, we wait on final pathology to differentiate these lesions. We have been able to correctly predict the pathologic diagnosis preoperatively in most cases by careful analysis of the MRI or computed tomography (CT) images. If there is internal signal streaking or inhomogeneity, lipoma-like liposarcoma is suspected. If a pure homogeneous, fatappearing image is present, lipoma is suspected, and we resect less margin tissue at surgery, opting for a true capsular resection. Thus far, we have not encountered a problem with this approach.
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