Spinal metastasis from acinic cell carcinoma of the parotid gland: a case report

Background contextAcinic cell carcinoma is the fourth most common tumor of the parotid gland, and spinal metastases are thought to be exceedingly rare. Only two other reported presentations are found in the literature, both presumably secondary to incomplete surgical resections.PurposeTo present the first known case of metastasis to the lumbar spine causing vertebral body involvement, after complete resection of the parotid gland.Study designCase report.MethodsA case of a patient who presented with low back pain and had imaging studies showing an expansive destructive lesion of the L4 vertebral body. The patient underwent a radical parotidectomy and radiation therapy for dedifferentiated, high-grade acinic cell carcinoma 2 years prior.ResultsThe patient underwent anterior L4 corpectomy and strut cage placement and posterior pedicle screw fixation from L2 to L5 on the same day, followed by radiation and oral chemotherapy 3 weeks later. Histopathologic examination confirmed metastatic dedifferentiated acinic cell carcinoma, present in the L4 vertebral body and overlying psoas muscle.ConclusionsThis case report underscores the importance of careful evaluation of patients presenting with back pain with a history of malignancy. It also calls into question the traditional low-grade classification ascribed to these tumors, given their ability to metastasize after complete excision and adjuvant therapy.