Light micrograph of a mesenchymal chondrosarcoma showing highly cellular sheets of small, undifferentiated round to spindle cells. Mesenchymal chondrosarcoma is an uncommon variant of chondrosarcoma. Unlike conventional chondrosarcoma, which is a tumour of adults and older individuals, mesenchymal chondrosarcoma occurs most commonly in the 2nd and 3rd decades of life with a female predilection. It frequently involves extra-osseous sites such as the orbit, meninges, soft tissues of the extremities and paraspinal region.