PMC4891406_01
Initial MRI of the upper right arm. A-B, Axial T1-weighted images through the proximal (A) and distal (B) aspects of the mass demonstrate a heterogeneous mass of predominantly high signal. The mass (arrow) has well-defined borders proximally that become ill-defined distally (arrowheads), adjacent to the neurovascular bundle. C, Axial T1-weighted, fat-suppressed image acquired after IV gadolinium demonstrates inhomogeneous enhancement. D, Post-processed subtraction image confirms intense enhancement. [PowerPoint Slide]
gr1.jpg
PMC4891406_01_gr1.jpg
fig1
An MRI demonstrated a 5.8(4.9(3.2-cm mass located between the heads of the triceps muscle (Fig 1).
A, Microscopic appearance of the proliferation of cellular spindle cells in short fascicles (Hematoxylin-eosin; x10). B, High-power view of fusiform cells shows uniform nuclei, admixed with extravasated erythrocytes and keloid-type collagen (Hematoxylin-eosin; x40). [PowerPoint Slide]
gr2b.jpg
PMC4891406_01_gr2b.jpg
fig2
Microscopically, the tumor consisted mostly of plump, immature-looking fibroblasts in short irregular bundles and fascicles accompanied by a dense reticulin meshwork containing a small amount of mature collagen (Fig. 2).
Axial T1-weighted MRI performed seven months later shows near complete resolution of the mass. A residual sub-centimeter lesion (arrow) has high signal similar to the original mass. [PowerPoint Slide]
gr3.jpg
PMC4891406_01_gr3.jpg
fig3
An irregular sub-centimeter region of abnormal increased T1 and T2-weighted signal remained present in the region of the prior 5.8 cm mass (Fig. 3).