Abstract 1571: Benign lipomatous lesions and liposarcomas have metabolic differences as identified in a high-resolution 1H and 31P MRS pilot study

Abstract

Abstract Adipocytic tumors present a spectrum of neoplastic disease including benign lipomas, atypical lipomatous tumors (ALTs), and malignant liposarcomas. Liposarcomas are the most common soft tissue sarcoma, accounting for approximately 20% of all adult soft tissue sarcomas [1]. Some liposarcomas are suspected to arise through dedifferentiation of ALTs, a process that is not well understood. Pleomorphic liposarcomas are high-grade, aggressive tumors with high metastatic potential and overall 5-year survival rate of 20-30% [3]. Distinguishing high-grade liposarcomas from benign and atypical lipomatous tumors can be a diagnostic challenge with implications for surgical and clinical management. The rate of misdiagnosis is approximately 30–40% following radiological detection [4], and 7–17% on histological evaluation [5]. De-identified human surgical samples were collected from the Dept. of Orthopaedic Surgery, JHU, School of Medicine Baltimore, MD. One tissue specimen from a benign pleomorphic lipoma and two tissue specimens from a pleomorphic liposarcoma were examined using 1H and 31P magnetic resonance spectroscopy (MRS) on 750 MHz MR spectrometer. Dual phase solvent extraction was performed to obtain aqueous and lipid phase spectra. Metabolites were quantified and changes were reported in terms of percentage change compared to levels in pleomorphic lipoma set to 100%. Depletion in branched chain amino acids (-10%), tyrosine (-15%), phenylalanine (-25%), lactate (-45%), pyruvate (-35-50%), acetate (-5-25%), and elevation in alanine (40%), succinate (35-60%), glycine (400-500%), histidine (15-25%), glucose (100%), glutamine (50%), glutamate (75%), and myo-inositol (300%) were observed in pleomorphic liposarcoma. 31P MRS of the aqueous phase revealed high levels of phosphocholine in the pleomorphic liposarcoma as compared to the lipoma (not detected). MRS analysis of the lipid phase identified depletion in lipid (-65%, CH3 peak at 0.9 ppm was quantified) and an increase in phosphatidylethanolamine (75%) and phosphatidylcholine (30%). Visible variations in TAG glycerol backbone (4.2-4.3ppm) and -CH=CH- peaks from polyunsaturated fatty acids at 2.8ppm and 5.3ppm were also observed. We are currently analyzing additional samples from several types of sarcomas to expand this study. Our preliminary data support investigating the use of 1H and 31P MRS of liposarcomas for differentiation between subtypes.