A Case of Intravascular Myopericytoma: A Painful Subcutaneous Tumor With an Intraosseous Lesion.

Myopericytoma is a rare perivascular myoid neoplasm that typically arises in the dermis or subcutaneous tissue, with an intravascular variant also reported. We present a case of an elderly man with a subcutaneous nodule in his lower leg that had persisted for four decades, accompanied by pain in the last several years. Imaging revealed a 20-mm elongated subcutaneous nodule along with a similar intraosseous lesion in the ipsilateral fibula. Histologically, the subcutaneous lesion appeared as a multinodular, vascular-rich tumor, characterized by myoid spindle cells arranged concentrically around vessels of varying sizes. These myoid cells were immunoreactive for smooth muscle markers. Additionally, the tumor exhibited both a feeding artery and a draining vein, mimicking a vascular malformation. Another portion of the subcutaneous nodule was surrounded by a venous-type vascular structure. These findings supported a diagnosis of intravascular myopericytoma, with its extension possibly being myopericytomatosis.