http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=99969
Summary
Pleomorphic liposarcoma (PLS), the rarest subtype of liposarcoma (LS; see this term), is an aggressive, fast growing tumor located usually in the deep soft tissues of the lower and upper extremities. It is characterized by a variable number of pleomorphic lipoblasts and, in contrast to dedifferentiated liposarcoma, it lacks any association with well-differentiated liposarcoma (see these terms).
The incidence is approximately 1/2,000,000 per year and it accounts for 5-10% of all LS cases.
PLS usually presents in older individuals with a typical age at diagnosis of 50-70 years. PLS is most commonly a firm, rapidly growing mass in the deep compartments of the lower and upper extremities but can also be located in the abdomen or chest wall in rare cases. PLS has a high (>50%) risk of metastasis, primarily to the lungs. Metastasis is rapid, often leading to death.
The etiology is unknown. PLS is characterized by highly complex chromosome alterations, including polyploidy and various chromosomal duplications, deletions and complex rearrangements.
When a mass is detected, computed tomography (CT) or magnetic resonance imaging (MRI) is performed. Chest and abdominal lesions do not require pretreatment biopsy unless resection is likely to be incomplete or highly morbid. Extremity lesions are generally sampled by multiple core biopsies to make the histological diagnosis of PLS. Histologically PLS contains a variable number of pleomorphic lipoblasts, with hemorrhage and necrosis commonly observed.
PLS can often be mistaken for myxofibrosarcoma or pleomorphic undifferentiated sarcoma (see these terms).
Treatment involves the surgical excision of the tumor and surrounding normal tissue. In rare cases amputation of the limb is necessary. Tumors that are large (>5-8 cm) or marginally resectable may be treated with preoperative chemotherapy. Adjuvant radiation is recommended if the surgical margin is narrow or positive for sarcoma. Lifelong follow-up is recommended in order to monitor for recurrence at the initial site as well as distant metastasis.
PLS has the poorest prognosis of all the LS subtypes. Five-year survival is 59%.