Growing Heterotopic Calcification in the Prevertebral Space of a Cervical Spine as a Late Complication of Irradiation: Case Report
A 74-year-old female with rheumatoid arthritis was admitted to the department of orthopedic surgery with pyogenic arthritis in her right elbow. She had a history of chemotherapy and radiotherapy due to tonsil cancer 21 years ago. She was referred for an otolaryngologic consultation due to chronic neck pain and swallowing difficulty on hospital day 7. The patient's complete blood cell count showed leukocytosis of 14.4 × 103/mm3 (normal range, 4.0-10.0 × 103/mm3) on admission, which decreased gradually and normalized at the time of the otolaryngologic consultation. Her C-reactive protein level was 16.9 mg/dL (normal range, 0-0.3 mg/dL) on initial examination and had fallen to 5.0 and 2.0 mg/dL on a follow up study performed on hospital days 5 and 8, respectively. No clinical or laboratory evidence of chronic renal failure or hypercalcemia was detected. She had no history of cervical spine trauma or infection. No cervical motion limitation was observed on a physical examination. Pharyngo-laryngoscopic findings were also unremarkable.\nA neck computed tomography (CT) scan revealed symmetric fatty atrophy of both the parotid and submandibular glands that seemed to be associated with the previous radiation therapy. Soft tissue swelling in the pharyngeal mucosal space, the retropharyngeal space, and the prevertebral space was observed with obliteration of the parapharyngeal space and fat planes around the carotid sheath. These findings suggested chronic radiation changes with fibrosis. The radiation changes were most prominent at the C2 and C3 levels, so these areas were thought to be included in the radiation field. The chronic neck pain and swallowing difficulty seemed to be due to radiation-induced changes in the pharyngeal mucosa and radiation-induced sialoadenitis. No evidence of tonsil cancer recurrence was detected.\nHowever, prevertebral soft tissue calcification was observed with a curvilinear configuration at the level of C2 and C3 (). The calcification was about 1.4 × 0.6 × 2.1 cm in size. It was irregularly shaped and partly fragmented. Prevertebral soft tissue thickening was noted at the C2 and C3 level (at C2: 9.1 mm; at C3: 8.2 mm). Additional prevertebral calcification was found at the C3-4 and C6-7 intervertebral disc levels, and they were thought to be associated with degenerative changes in the intervertebral discs (). The C2 and C3 bodies and posterior elements showed osteopenia and coarsening of trabeculae. suggesting radiation osteitis or osteoradionecrosis. Mild degenerative changes were observed in the lower cervical spine. No significant findings suggesting atlantoaxial involvement of rheumatoid arthritis were found.\nA neck CT scan obtained 7 years ago demonstrated calcification at the same site (). The calcification was about 0.9 × 0.5 × 1.5 cm in size and was ovoid-shaped and smooth-margined. The retropharyngeal and prevertebral soft tissue swelling was slightly more prominent compared with that of the later study. Findings of C2 and C3 osteoradionecrosis were not significant 7 years ago.\nFollow-up C-spine lateral radiography after 1 year showed no change in size or configuration of the calcification (). Although not histopathologically confirmed, the lesions were thought to be benign because they grew slowly and remained unchanged for at least 1 year. Based on the clinical course and association with previous radiation therapy, the diagnosis was heterotopic calcification in the prevertebral space as a late complication of radiation therapy.