Perineural spread in pelvic malignancies can be an alternate explanation for pelvic bony metastases rather than hematogenous spread. A report of two cases.

We propose that pelvic malignancies can spread to bone and cause bony metastases using nerves as conduits. We reviewed two cases of pelvic malignancy with perineural spread of bladder cancer and prostate cancer. In a patient with prostate cancer, we identified six lesions that were positive on the (11)C-choline PET/CT scan and MRI; in a patient with bladder cancer, we identified two lesions positive on the (18)F-deoxy-glucose PET/CT scan and MRI. We carefully reviewed the imaging studies, and using established sclerotome maps we identified spinal nerves supplying each of eight pelvic bony lesions. All these spinal nerves showed evidence of tumor infiltration with extension toward the affected bones. We theorize that perineural tumor spread may serve as an additional mechanism of pelvic osseous metastases in pelvic malignancies.