High-Grade Myxofibrosarcoma Showing Pleomorphic Hyalinizing Angiectatic Tumor-like Appearance: A Case Report

ABSTRACT

Myxofibrosarcomas (MFSs), which consist of multiple nodules with a variable cellular population in a myxoid matrix, are primarily located in subcutaneous tissue. Pleomorphic hyalinizing angiectatic tumors (PHATs) are rare soft-tissue tumors characterized by a proliferation of highly pleomorphic spindle or polygonal cells and abundant ectatic blood vessels in cellular or myxoid stroma. We present here an unusual case of a high-grade MFS with a PHAT-like appearance. A 67-year-old man presented with an asymptomatic subcutaneous mass in the right forearm. The tumor had myxoid, hypo-, and hypercellular areas with highly pleomorphic spindle or polygonal tumor cells that showed frequent mitoses and nuclear pseudoinclusions. Foci of punctuate necrosis and inflammatory infiltration were present throughout the tumor, and abundant ectatic, thick-walled vessels containing blood clots were noted. The tumor cells were immunohistochemically positive for vimentin but negative for CD34, S-100 protein, smooth muscle actin, desmin, and bcl-2.