Metastasis of spine from adenoid cystic carcinoma of the parotid gland: two case reports 

BACKGROUND: Spinal metastasis from adenoid cystic carcinoma of the salivary gland is extremely rare. We present two interesting cases of spinal metastasis from adenoid cystic carcinoma of the parotid gland. CASE SUMMARY: A 29-year-old Persian male and a 48-year-old Persian female presented with parotid gland mass. The two patients received parotidectomy and radiotherapy. The pathological examination result was adenoid cystic carcinoma. Because of intractable back pain, patients were referred to the hospital after 7 years and 9 months, respectively. Both cases underwent spinal surgery. Histopathology confirmed spinal metastasis from adenoid cystic carcinoma of the parotid gland (case 1: T6, T12, and L1; case 2: T12). Anterior corpectomy of T12 and lateral screw fixation at T11 and L1 were done in case 2. Posterior spinal fusions from T2 to L3 and from T10 to L2 were performed in case 1 and case 2, respectively. Both patients showed good clinical improvement. The last follow-up (case 1: 24 months; case 2: 6 months after surgery), plain radiographs and computed tomography scan showed good fusion without instrumental failure and magnetic resonance imaging revealed good decompression of the spinal cord of both cases. CONCLUSION: Although spinal metastasis from adenoid cystic carcinoma of the parotid gland is extremely rare, it is necessary to be careful in the differential diagnosis.