Fig. 2

Gross appearance and microscopic pathology of the tumour. a, After dividing the mass, it appeared as a solid tumour exhibiting a tube-like structure with vascular endothelium; b, Histologically, the mass was displayed as proliferating spindle-shaped smooth muscle cells lacking nuclear atypia and homogenous red-dye substances; c, the spindle cells showed positive immunostaining for smooth muscle actin (SMA); d, the spindle cells showed positive immunostaining for desmin; e, the spindle cells showed positive immunostaining for Ki-67 (labelling 3%); f, the spindle cells showed negative immunostaining for HMB45