3.2 Diagnostic strategy
An ultrasonogram can confirm the presence of a clinically doubtful soft tissue mass. More expensive exams are computerized tomography scan and magnetic resonance. Both have the advantage of being useful as staging presurgical exams, while ultrasound must be followed by one of the two if a tumor is confirmed. Computerized tomography and magnetic resonance scans are roughly equivalent, even if magnetic resonance can give coronal and sagittal views in addition to transaxial ones, and may better contrast muscles and vessels. The execution either of computerized tomography or of magnetic resonance is therefore recommended preoperatively.
3.3 Pathological diagnosis
A biopsy is recommended of virtually all soft tissue masses not known to the physician or the patient to be unchanged from years before.
It is recommended that biopsy is planned by a surgeon involved in the treatment of soft tissue sarcomas. In fact it can endanger the feasibility of subsequent adequate conservative surgery if improperly done. In particular the biopsy tract will have to be removed at the time of definite surgery. Hematomas should be avoided. Excisional biopsy entails in any case the need for radicalization after pathological diagnosis, and so is generally not done save for the smallest lesions. Difficulties may arise in localizing the site of the tumor thereafter. For extremity sarcomas the use of a pneumatic tourniquet has never been proven, and is therefore not recommended. An incisional open biopsy is generally regarded as the standard option, on a type C basis. Its drawback may be the occurrence of local complications (up to 15-20%) and that it is often done inappropriately. In fact, in most cases, a Tru-cut biopsy can be sufficient to provide the clinician with the diagnosis of soft tissue sarcoma and the "minimal" malignancy grade. In this regard, the diagnosis of low grade sarcoma should be viewed with caution because the tumor can be heterogeneous and the specimen can be outside high malignancy areas. Actually, the accuracy of Tru-cut biopsies depends on the clinician's and pathologist's experience and on the kind of diagnostic problem, but sensitivity and specificity for the diagnosis of sarcoma may be as high as 95%. Tumor grade may be correct in >85of cases. For these reasons, Tru-cut biopsy can be now considered an alternative standard option on a type R basis (2.III). On the contrary, fine needle aspiration is appropriate for individual non standard clinical use on a type 3 level of evidence (2.IV) by institutions which have gained experience on its use. Overall accuracy may be as high as 90%. The Tru-cut biopsy as well as fine needle aspiration should, in most instances, be done under CT guidance.
The diagnosis of a soft tissue sarcoma may be difficult and the rarity of soft tissue sarcomas adds to such difficulties. In 5-20of cases a second pathological opinion does change the diagnosis from sarcoma to a non sarcoma. It is recommended that the histopathological evaluation be performed by a pathologist experienced with soft tissue sarcomas.
It is recommended that pathological diagnosis provides the clinician with histotype and malignancy grade. The reproducibility rate among different pathologists with regard to the histotype averages >45-60%. The reproducibility rate with regard to the malignancy grade seems higher, around 75%. Malignancy grade is more important for the clinician than the histotype, and should be specified even when the histotype cannot be ("sarcoma, not otherwise specified"). Even when the histotype might be regarded as automatically entailing a specific malignancy grade, the pathologist should state it explicitly in the pathological report.
Cytogenetics and electron microscopy may allow the specification of the histotype in those cases in which it otherwise would not be specified.
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