Large well-circumscribed lobulated intermuscular soft tissue mass, surrounding the proximal fibula. It shows a homogeneous high signal on T1 and T2, attenuated on fat sat sequences with no thickened septa, enhancement or evidence of local invasion. There is an inter-tibiofibular and retrofibular extension encasing the common fibular nerve and its superficial and deep branches. Moderate thickening of the adjacent cortical fibula.