The doctor will obtain your child’s medical history, perform a physical examination, and order a battery of tests including a complete blood count (CBC), liver function tests, and other blood tests including electrolytes and kidney function levels. Ultrasounds, computerized tomography (CT) scan, and magnetic resonance imaging (MRI) are often done to evaluate the size of the mass and its relationship to surrounding structures. Once the mass has been examined through imaging, a biopsy is needed so the cells can be tested to determine whether the mass is cancer and, if so, what type. The three kinds of biopsy are:

•  A needle biopsy, usually done through the skin (sometimes under the guidance of ultrasound or CT scan).

•  An incisional biopsy, where the surgeon only removes a small piece of the tumor.

•  An excisional biopsy, where the surgeon tries to remove most or all of the tumor.

The biopsy should be done by a surgeon who has experience with pediatric solid tumors so:

•  Enough tissue is removed to allow for a definite diagnosis; but

•  The procedure does not make it more difficult for the entire mass to be removed in a future surgery (if additional surgery is needed).

For further information on these procedures, see Chapter 14, Surgery.

Tests are necessary to establish a specific diagnosis, especially because non-rhabdomyosarcoma soft tissue sarcomas can appear very similar, even at the microscopic level. The different types of tumor cells have distinctive molecular and genetic characteristics that can be used to help doctors establish the exact diagnosis, determine a prognosis, and find the most appropriate treatments.