How to get a liposarcoma diagnosis

Diagnosis - tumor orthopedics

Epidemiology
Soft tissue sarcomas are rare with an incidence of 2-3 new cases per 100,000 population and year and account for 1-2% of all malignant tumors in adulthood. In Germany, around 3,000 new cases are expected each year. The peak of the disease is in the second half of life and women are slightly more likely than men. Soft tissue sarcoma occurs most frequently in the area of ​​the lower extremity (approx. 45%), followed by the upper extremity (15%), the trunk and the retroperitoneum. 2/3 of the tumors are located extracompartmental and 1/3 intracompartmental.
Soft tissue sarcomas represent a very heterogeneous group of malignant tumors. They include all tumors of non-epithelial tissue (muscles, adipose tissue, connective tissue, vessels, etc.). About 50 different entities can be differentiated immunohistologically. The liposarcoma is the most common representative with more than 20%. The etiology of soft tissue sarcomas is largely unknown. In rare cases, they can be radiation-induced and occur more frequently in Li-Fraumeni syndrome, neurofibromatosis type I and Gardner syndrome, so that a genetic predisposition exists at least in these cases.
At the time of the primary diagnosis, around 30% of the patients have a stage I (UICC, 2003), 30% a stage II, 20% a stage III and 20% a stage IV.

Diagnosis
The most common primary symptom of soft tissue sarcoma is swelling. In the area of ​​the retroperitoneum, abdomen and thorax, the symptoms can vary widely and are mostly non-specific. Of around 300 operated soft tissue tumors, only one is malignant. On the one hand, this unequal ratio makes it easy to forget the soft tissue sarcoma in the differential diagnosis and, on the other hand, makes the primary diagnosis all the more difficult. With the exception of fatty tumors (lipoma, liposarcoma), histological assignment using MRI is not possible. MRI can also be helpful in differentiating between tumor and peritumoral edema, especially since tumor cells are present in 66% of cases in peritumoral edema. Resection planning should only be undertaken with knowledge of the MRI.
Positron emission tomography (PET) as functional metabolic imaging is currently of no relevance outside of clinical studies. There are first test results that allow an assessment of the grading by means of PET in the primary diagnosis of soft tissue tumors and can be used in the response assessment in the context of neoadjuvant therapy. Angiography is only rarely indicated for special preoperative questions.
After completion of the clinical and imaging diagnostics, if a malignant soft tissue tumor is suspected, histological confirmation is mandatory. Only small (<3 cm) and superficially localized tumors can be resected primarily without functional restrictions. All other tumors are primarily biopted. The biopsy already requires an interdisciplinary concept. In centers, punch biopsies lead to a correct diagnosis (typing and grading), punch biopsies in 91% and open biopsies in around 98%. The biopsy must be planned with the oncological surgeon / tumor orthopedic surgeon so that the tumor can be reached by the shortest route and the definitive tumor resection is not hindered. Open biopsies are performed on the extremities with a longitudinal skin incision. In the case of punch biopsies, an exact anatomical description, better a tattoo, should be carried out so that the biopsy channel could be in the resected material during the definitive tumor resection, which may only be carried out after neoadjuvant therapy. An incorrectly performed biopsy can not only make the definitive resection more difficult, in the worst case it can even make a mutilating surgical procedure up to amputation necessary. Only after the diagnosis has been completed can the tumor stage be determined and the therapeutic consequences derived.