Liposarcomas are the most frequent soft-tissue sarcomas. The World Health Organization Classification of Tumours [
1] divides these tumours in four main histological types: well-differentiated, myxoid, round cell and pleomorphic types. As myxoid and round cell tumours share the same cytogenetic abnormalities, namely the traslocation t(12;16)(q13;p11) leading to the fusion of the genes
DDIT3 and
FUS with generation of a hybrid protein FUS/DDIT3, some authors consider both lesions as a continuum of the same disease. This possibility seems to be supported by the frequent finding of areas of round cells in myxoid liposarcomas, which has been considered a marker of poor prognosis when representing 5% or more of the mass in localized myxoid liposarcoma. In our second patient the cytogenetic analysis performed in paraffin-embedded tissue from the tumour confirmed the typical traslocation; in the first patient the specimen was not suited for cytogenetic analysis.
In the present work we report two patients with a multicentric myxoid liposarcoma. This entity seems to be rather infrequent and some authors consider it different from ordinary liposarcoma due both to multicentric presentation and to a more aggressive behaviour [
2,
3]. There has been some debate whether these multicentric tumours truly represent synchronous lesions at different levels or a haematogenous spread from one primary lesion [
4]. Interestingly the multicentric tumours tend to spare classical metastatic sites of sarcomas, like the liver, the lungs or the bone and affect rare locations, like the pleura or the lymph nodes, as happened in one of our patients [
5]. This fact seems to speak against a possible metastatic explanation for multicentricity. The identification of the same cytogenetic abnormalities in all the multicentric lesions cannot be considered either definite proof of their metastatic origin, for they might still be multicentric synchronous or metachronous lesions related to a common aetiopathogenic factor [
6].
Another important fact highlighted by our cases is the importance of performing a complete imaging study of patients with myxoid liposarcomas of the limbs, mainly to exclude possible multicentric lesions [
7].
As for therapy it seems surgery remains as the mainstay of treatment [
8]. In our patient the initial surgical management included limb amputation before diagnosis of multicentrity was performed. This form of therapy might be considered rather too aggressive; if we had known that the patient had more lesions, we would have applied neoadjuvant chemotherapy for bulk reduction and perform a more conservative surgical approach after it, like we did in the second case. However, at the time of the first surgery we had no sign of multicentric involvement by the tumour and we chose the possible curative alternative for a young person in a good general health. Nevertheless, bulk reduction followed by surgery has not seemed to change the fate in our second case, for the tumour has shown the same tendency to recur and has behaved as aggressively as in the first case.
As prognosis seems to be poor, chemotherapy and radiotherapy seem indicated both in the neoadjuvant or adjuvant settings. As these multicentric tumours are rare, it is difficult to determine which regimen could be the best in these patients. Nevertheless, the literature does not indicate a significant improvement of the outcome regardless of the chosen therapy.
4 Pilar López-Criado,1 Mariano López-Franco,2 Telma Meizoso,4 and Carolina Calvo3
This article has been 
