Fine needle aspiration
It is always advised to do a punction of a tissue mass to make the distinction between a tumour and other tissue masses with a similar aspect (tissue masses such as fat lumps, accumulations of encapsulated liquids, inflammations, abscesses). On the other hand, the nature of fibrosarcomas can be deceitful and punctions false-negative. When cancer cells are found in the content of a tumour aspiration, this proves the tissue mass is a tumour/metastasis. When no cancer cells are found, this does not exclude that the tissue mass is cancerous.
For a definitive diagnosis it is necessary to do a biopsy. Tissue can be obtained by taking a small sample via a big needle, by resecting a part of tumour tissue or by excising the tumour in its entirety.
In order to exclude lung metastases, it is advised to take radiographic photos of the thorax. The radiographic photos, ultrasound, CT/MRI scan of the primary tumour location can be necessary when the tissue mass invades underlying structures and we want to know how much the underlying structures are affected. This way, the elimination of the tumour can be better planned. It is a.o. known that ultrasound will detect a need for larger margins in 19% of cases, with a CT scan this is true for 65% of cases.
Via regular histopathology it is not always evident to differentiate a fibrosarcoma from other tumour types. Therefore, it is sometimes necessary to use antibodies that bind certain markers present in the tissue of fibrosarcomas. If these markers bind the sampled tissue, this means that there is a high probability it’s a fibrosarcoma. The tissue grade is based on the degree of differentiation (how well the different elements in the tissue are recognizable), the multiplication index (how much the cancer cells are multiplying) and necrosis (tissue death). The less differentiated and the higher the multiplication index and level of necrosis, the worse the prognosis is.
|Grade||score||differentiation score||mitosis score (mitosis/field)||tissue death|
|Grade 1||<=3||1 = well differentiated||1 = 0-9||1 = not present|
|Grade 2||4-5||2 = moderately differentiated||2 = 10-19||2 = <=50%|
|Grade 3||>=6||3 = not differentiated||3 = > 19||3 = > 50%|