Sacral Radiculoplexopathy Caused by Direct Perineural Spread of Carcinoma Prostate Diagnosed in Ga-68 PSMA PET/CT

Certain abdominal and pelvic malignancies present with sensory, motor or autonomic symptoms suggestive of nerve root involvement. Perineural spread of tumor is an emerging explanation of such presentations. This could be seen in carcinoma prostate. In this case report, we present one such case of carcinoma prostate with local recurrence and perineural spread of tumor causing unilateral sacral plexopathy. The patient presented with persistently elevated serum prostate-specific antigen and symptoms of lower backache and paraesthesia in the back of the thigh. On evaluation with Gallium-68 prostate-specific membrane antigen positron emission tomography/computed tomography (Ga-68 PSMA PET/CT), perineural spread of recurrent lesion to S2-S4 nerve roots was identified. The patient received radiotherapy for local recurrence and improved symptomatically and is under follow-up. Carcinoma prostate patients presenting with neurological symptoms should be carefully evaluated to rule out perineural spread of tumor. Ga-68 PSMA PET/CT has proven to be a useful modality in diagnosing such cases.