Diffuse skeletal muscle metastases from sacral chordoma

Chordomas are rare, slow-growing tumors arising from cellular remnants of the notochord. They account for 1-4 % of primary malignant bone tumors and usually occur in the axial skeleton, most commonly the sacrum. Although typically locally recurrent, chordoma metastasis rates as high as 10-42 % have been reported. While spread to multiple organ systems has been documented, metastatic disease to skeletal muscle is extremely rare. We present a case of extensive, multifocal skeletal muscle metastases developing in the setting of recurrent sacral chordoma. Our literature search found only one additional case of metastatic chordoma to a single skeletal muscle.