(A) Trapezius (TP) ultrasound scan, longitudinal slice on cephalic edge. A hypoechoic mass is observed, homogenous in appearance and completed contained within the thickness of the muscle with no contact with the fascia (F) or subcutaneous cellular tissue (SCCT). The power Doppler signal is essentially concentrated in peripheral regions. (B) NMR of the shoulder, DP/SPIR sequence to remove fatty tissue. Transversal slice of the trapezius (arrow). In its interior a hyperintense structure with well defined edges is enhanced and this occupies almost all of the muscle matter (*). (C) NMR of the shoulder, T1 sequence, sagittal slice. In this projection the longitudinal extension of the trapezius (arrow) is appreciated and the occupation by the same fusiform, hypointense structure, with respect to the adjacent tissues. (*).