Abstract
A metastatic multicentric neurofibrosarcoma of the lumbosacral plexus in an adult cow is described. The left lumbosacral plexus was obliterated by a mass which extended through the intervertebral foramen into the spinal canal and between the dorsal arches of the fifth and sixth lumbar vertebrae. A closely associated (possibly contiguous) mass extended into and separated the left sacroiliac joint. Multiple similar masses involved peripheral nerves and skeletal muscles of the pelvis, pelvic limbs, and abdominal wall. Metastatic lesions were scattered throughout the lungs. The lumbosacral lesion and all other masses consisted of interwoven bundles of loosely cohesive, elongated cells separated by variable collagenous matrix. Many neoplastic cells were positive for S-100 protein. Ultrastructurally, fibroblastic cells were mixed with scattered cells possessing schwannian characteristics.