Review Question - QID 212983

The patient has a well-differentiated liposarcoma (WDLPS), also known as an atypical lipomatous tumors (ALT), which results from MDM2 amplification. The best step in treatment is marginal resection without radiation.

Liposarcomas are a heterogeneous class of sarcomas with differentiation towards adipose tissue. Well-differentiated liposarcomas are a low-grade subtype of liposarcomas that result from MDM2 amplification. Due to the low risk of local recurrence, they are amenable to marginal resection without radiation. Intermediate-grade and high-grade liposarcomas (such as round cell liposarcomas, pleomorphic liposarcomas, and dedifferentiated liposarcomas), on the other hand, should be treated with wide resection and adjuvant radiation.

De Vita et al. published a review on the current classification, treatment options, and new perspectives in the management of adipocytic sarcomas. They report that ALT/WDLPS is characterized by the amplification of 12q13-15 chromosome region which encodes for several potential oncogenes including MDM2, CDK4, HMGIC/HMGA2, SAS, GLI, and DDIT3/CHOP, with MDM2 being the most frequently amplified oncogene.

Mariño-Enriquez et al. published a study characterizing the clinical, histologic, and immunohistochemical features of atypical spindle cell lipomatous tumors. They reported that all cases consisted of a poorly marginated proliferation of mildly atypical spindle cells set in a fibrous or myxoid stroma, with a variably prominent admixed adipocytic component showing variation in adipocyte size and scattered nuclear atypia, frequently with univacuolated or multivacuolated lipoblasts. They found that 87% of patients (63/72) were alive at 4-year follow-up with no evidence of recurrence or metastatic disease.

Figures A and B are axial T1- and T2-weighted MRIs demonstrating a large mass that is primarily fatty, consistent with a liposarcoma. Figure C is a histological slide showing lipocytes with thick fibrous septae and atypical lipoblasts.

Incorrect Answers:
Answer 3: Well-differentiated liposarcomas are best treated with marginal resection without radiation.
Answers 2 and 4: A t(2;13) translocation is associated with alveolar rhabdomyosarcoma.
Answer 5: A t(12;16) translocation is associated with myxoid liposarcoma.