Abstract: Objective    To explore the barrier effect of the middle layer of superficial  fascia against the proliferation of lipoma by MRI imaging and the observation of the growth pattern of the lipoma in the spine and extremities.    Methods    117 lipoma cases（total 121 sites） ( 48 males, 69 females) were collected in this retrospective study, all of which were treated with  operation performed in Beijing Chao-yang Hospital. All the lesions were confirmed by the histopathologic results. The barrier role of the fascia at the site of the tumor was identified in operation and compared with the preoperative MRI. The deep fascia, superficial fascia, and the middle layer of superficial  fascia were identified and the relationship between the lipoma with those structures were observed in operation and in MRI images.     Results    The average age of patient was 52.2（15-82）ys ;  52 case（ 44.4%）in left, 57 cases（48.7%） in right,  6 case （5.1%） in bilateral and 2 cases（ 1.7%）in midline; according the site of lipoma ，there was 9（7.5%） in the neck,7（5.8%） in the upper back, 28（23.1%） in the shoulder,19（15.7%）in the arm , 9（7.4%）in the forearm, 4（3.3%）in the hand, 42（34.7%）in the thigh , 3（2.5%）in the leg; according the position of lipoma ,47cases（ 40.2%）was in the muscule, 21 cases（17.9%）was under the deep fascia, 28 cases（23.9%）between the deep fascia and the middle layer of the superficial  fascia, 7 cases（5.9%）between the skin and the middle layer of the superficial fascia, 11 cases(9.4%) in the intermuscular space ;  57 cases (48.7%)  was lobubar shape ,49 cases（41.9%）more ellipticaland  11 cases（9.4%）flat according to the tumor shape, they are bordered with normal tissue and can be separated in operation;    4 cases（ 3.4%） was hibernoma , 2 cases（ 1.7%）angiolipoma,  101 cases（86.3%） typical lipoma, 10 cases（ 8.4%）fibrolipoma in the histopathologic classification. Conclusion   The middle layer of superficial fascia was a mesh fascia that is widely located in spine and extremities. It plays an important role as a natural barrier against the proliferation of lipoma. It was also found that the deep fascia and muscle septum have a strong barrier and restrictive effects on tumors.  

Key words: The superficial fascia; ,  The middle layer of superficial fascia; ,  Lipoma; ,  , Natural barriers