title: Prognostic factors for the recurrence of myxoid liposarcoma: 20 cases with up to 8 years follow-up.
abstract: BACKGROUND
  Myxoid liposarcomas (MLS) are the second most common type of liposarcoma. Although some MRI findings are distinctively characteristics of MLS, the diagnosis can be tricky in tumors with a large portion of round cells (RC). Known predictors of an unfavorable outcome include age, tumor size, high RC content and positive resection margins. The goal of this retrospective study was to define prognostic factors for recurrence, with special emphasis on the percentage of RCs and medical care provided in a non-specialized center.
  
  
  METHODS
  Twenty patients (11 women, 9 men) with a mean age of 44.3 years (18-73) were reviewed after a mean of 55.9 months. Six of these patients had been operated at a non-specialized center. The diagnostic MRI was read by a specialized radiologist and the resection procedures performed by two specialized surgeons. Tumors were labeled as either "pure myxoid liposarcoma" or "myxoid/round-cell liposarcoma". The local recurrence-free survival rate and mortality rate were calculated.
  
  
  RESULTS
  Fifteen patients had undergone an MRI during the initial assessment. The typical MRI findings of MLS were present in four of them. The MRI suggested a non-specific lesion in the other 11 patients. After correlation with pathology findings, these tumors contained more than 5% round cells. The fourteen patients treated at our facility had undergone a biopsy, while none of the ones treated outside did. Five patients had R0 resection margins and 15 had R1 margins. Prognostic factors for recurrence consisted of age, tumor size >10 cm, R1 resection margins, FNCLCC grade 2+R1 margins, medical care at a non-specialized center, and >5% round cells. There were eight local recurrences and three metastases (15%). Two patients died (90% overall survival rate).
  
  
  CONCLUSIONS
  The risk of local recurrence was 3.86 times greater in this study when the tumor contained more than 5% RCs, which is consistent with published data. The MLS diagnosis was made only four times based on the initial MRI because misleading nature of high RC tumors. R1 resection margins are a risk factor for local recurrence. However, cases with R1 margins have a recurrence rate that is similar to R0 cases when the surgery is performed at a specialized cancer center. Treatment of MLS in a non-specialized center is a key negative prognostic factor. The reported rate of metastasis varies. Atypical extrapulmonary localizations are common, and often multifocal. MRI has been shown to be superior at detecting secondary lesions and some have suggested that a full-body MRI should be performed.
  
  
  CONCLUSIONS
  Prognostic factors for the recurrence of myxoid liposarcomas have been identified. MRI analysis is not definitive and must be supplemented by a biopsy.
authors.affiliation: Service de chirurgie orthopédique, traumatologique et des tumeurs musculo-squelettiques du Pr Curvale, hôpital Nord, chemin des Bourrely, 13915 Marseille cedex 20, France.
authors.forename: M
authors.initials: M
authors.lastname: Lemeur
authors.affiliation: Service de chirurgie orthopédique, traumatologique et des tumeurs musculo-squelettiques du Pr Curvale, hôpital Nord, chemin des Bourrely, 13915 Marseille cedex 20, France. Electronic address: jeancamille.mattei@gmail.com.
authors.forename: J-C
authors.initials: JC
authors.lastname: Mattei
authors.affiliation: Service de radiologie du Pr Chagnaud, hôpital de la Conception, 147, boulevard Baille, 13005 Marseille, France.
authors.forename: P
authors.initials: P
authors.lastname: Souteyrand
authors.affiliation: Service de radiologie du Pr Chagnaud, hôpital de la Conception, 147, boulevard Baille, 13005 Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: Chagnaud
authors.affiliation: Service de chirurgie orthopédique, traumatologique et des tumeurs musculo-squelettiques du Pr Curvale, hôpital Nord, chemin des Bourrely, 13915 Marseille cedex 20, France.
authors.forename: G
authors.initials: G
authors.lastname: Curvale
authors.affiliation: Service de chirurgie orthopédique, traumatologique et des tumeurs musculo-squelettiques du Pr Curvale, hôpital Nord, chemin des Bourrely, 13915 Marseille cedex 20, France.
authors.forename: A
authors.initials: A
authors.lastname: Rochwerger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001706:Biopsy; D005260:Female; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D006801:Humans; D018208:Liposarcoma, Myxoid / Q000401:mortality / Q000473:pathology*; D035002:Lower Extremity; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000401:mortality / Q000473:pathology*; D009364:Neoplasm Recurrence, Local / Q000401:mortality; D009367:Neoplasm Staging; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D015996:Survival Rate / Q000639:trends; D013997:Time Factors; D055815:Young Adult
keywords: Imaging; Myxoid liposarcoma; Prognostic factors; Recurrence; Round-cell percentage; Specialized center