Abstract
Supplementary Figure 1. Higher magnification hematoxylin and eosin stain reveals a cellular dermal and subcutaneous neoplasm composed of uniform spindle cells arranged in a characteristic storiform pattern. There is infiltration into the surrounding adipose tissue in a characteristic "honeycomb" pattern, with tumor cells dissecting between individual fat cells. There is minimal cytologic atypia, low mitotic activity, and no necrosis.
Supplementary Figure 2. Immunostaining for CD34 shows strong and diffuse membranous and cytoplasmic positivity for CD34 in the neoplastic spindle cells throughout the lesion. The background adipocytes are negative, which highlights the honeycomb infiltration pattern of the tumor into subcutaneous fat.