My personal bias is for surgical excision with wide margins of any questionable mass. However, this is not always possible.

If a lesion is inoperable, it is sometimes necessary to biopsy in order to find out what it is.  A diagnosis is absolutely necessary before starting treatment.  How else would you know what to treat the tumor with? Remember that 7.5% of LMS patients will develop a second primary cancer.  A new lump in an LMS patient is not always an LMS metastasis. 

When a biopsy is required, it should be carried out after a complete imaging work-up [which sometimes allows a correct prebiopsy diagnosis] to indicate the biopsy modality, approach and site. Complete imaging is also mandatory to stage the tumor, plan the surgical approach and technique, and show fine details of any occult tumor spread. [1, 15, 16]  Most importantly, to accurately diagnose and classify most sarcomas, an expert sarcoma pathologist (or cytopathologist in the case of FNA) to examine the specimen is paramount.   This is particularly true of FNA where the sample of tissue provided to establish a diagnosis is quite limited.

If the tumor cannot be removed completely with wide margins, if a biopsy is inevitable, the biopsy should be planned and done by doctors expert in the site of the tumor, and be the least invasive possible.  However, a core needle biopsy might give better results with fewer passes than a fine needle biopsy, and be less invasive than an open biopsy.  Discuss with your doctor, as well as his personal record of complications with the proposed procedure.  Needle biopsies should be taken seriously as they can indeed cause seeding along the path of the needle, and might be responsible for metastatic spread as well.  The best course of action would be to surgically remove the tunnel the needle had followed in the next surgery.  
If the clinical and Xray information favors a diagnosis of malignant or aggressive bone tumor, the patient should be referred to an experienced orthopedic oncologist without any additional tests or biopsies.  If a soft tissue mass is 5cm or larger, and especially if it is deep, the patient should also be referred to an orthopedic oncologist, because of the relatively high probability that the mass is malignant. [14]  The risk of implantation metastases induced by fine-needle biopsy warrants consideration in patients with abdominal malignancies since it may compromise the outcome of radical surgery. It should only be performed when the result of the procedure has a direct impact on the choice of therapy. [30]
