Management strategy for subfascial lipomatous soft tissue tumors

Purpose of the study The prognosis of subfascial lipomatous soft tissue tum ors depends greatly on their histological type ranging from benign lipomas that cause little local or general problems to the severe prognosis of lipo sarcomas that exhibit both local and distant extension. However, the clinic al presentation of the two types of tumors may be similar and thus quite mi sleading, sometimes leading to inappropriate management and severe conseque nces. The main objective of this study was to determine whether the preoper ative work-up in patients treated for musculoskeletal tumors within our rec ruitment zone is adequate, allowing appropriate therapeutic decisions. In a ddition, we wanted to know what explorations are most pertinent for the dif ferential diagnosis between benign and malignant subfascial lipomatous soft tissue tumors. Material and methods Thirty-seven patients with subfascial tumors were incl uded in this study. There were 16 with benign lipomas and 21 with liposarco mas. All the patients with benign lipomas but only 9 (43%) of those with li posarcoma had received initial care within our recruitment zone before fina l diagnosis. Two cases had been referred after biopsy and 1 after resection by morcellation; the 9 others were secondary referrals after tumor recurre nce. Only 5 of these 12 referred patients had had an MRI exploration prior to surgery, 2 with an erroneous interpretation. An MRI series was obtained for all the patients with benign lipoma and for the 9 with liposarcomas who attended our units directly. A biopsy was also obtained in case of suspect ed liposarcoma. Two radiologists blinded to the final diagnosis reviewed th e available MRI to assess their diagnostic value for subfascial lipomatous soft tissue tumors. Results No case of recurrence, after marginal resection (10 cases) was note d for lipomas. Six are under observation with regular MRI (with no change i n size or signal). Four patients with liposarcoma died from their disease ( 19%) and 2 who had undergone "curative" resection had a recurrence (12%). I ncorrect or imprecise (incomplete, incorrectly interpreted or no MRI) preop erative diagnosis led to additional morbidity with 3.4 surgical procedures (mean per patient) compared with 1 in patients who had had undergone a comp lete work-up and whose diagnosis was established after multidisciplinary di scussions. Among the diagnostic elements available before pathology, only M RI findings had diagnostic value for subfascial lipomatous soft tissue tumo rs: for benign lipoma positive predictive value = 92% and negative predicti ve value = 93%. Discussion The clinical course of the benign lipomas and the sarcomas in th is series confirm the radically different prognosis of these two tumors, bo th in terms of local extension and survival. Inadequate management in the i nitial diagnostic stages-i.e. lack of MRI with contrast injection, biopsy a nd multidisciplinary interpretation prior to treatment-raises the risk of h igher morbidity, particularly a significantly greater number of reoperation s, and progression to a higher grade of malignancy for two tumors. Our retr ospective analysis enabled us to develop a decision making tree for patient s with subfascial lipomatous tumors. Prospective validation will be necessa ry.