Intravascular fasciitis. (A) The mass is composed of spindle cells arranged in an intersecting pattern. (B) The mass extends through the vascular walls into the surrounding connective tissue. (C) Elastin stain reveals remnants of elastic lamina partially surrounding the lesion. (D) The nuclei of the spindle cells are uniform with tapered ends and prominent nucleoli. (E) Multinucleated giant cells are scattered within the mass. (F) Infiltrating lymphocytes and extravasated red blood cells are present. (G) The spindle cells are positive for SMA. (H) The spindle cells are focally positive for muscle specific actin. (I) The spindle cells are negative for S-100.