retropharyngeal calcific tendinitis is an uncommon benign process caused by calcium hydroxyapatite deposition and inflammation in the longus colli muscle ( lcm ) , which is located on the anterior surface of the vertebral body , extending from the atlas to the third thoracic vertebra ( 1 , 2 ) . clinical presentation of retropharyngeal calcific tendinitis is often characterized by non - specific symptoms such as acute or subacute neck pain , dysphagia or odynophagia , and low grade fever . laboratory tests may demonstrate mild leukocystosis and slightly elevated erythrocyte sedimentation rate ( esr ) ( 2 ) . this set of conditions can easily be misdiagnosed due to their rather non - specific presentation and rare occurrence ( 2 ) . diagnosis is usually based on the recognition of amorphous calcification anterior to c1 - 3 , and prevertebral soft tissue swelling on plain radiographs and computed tomography ( ct ) ( 1 , 3 - 5 ) . this is the first report of acute retropharyngeal calcific tendinitis with calcification anterior to the c4 - 5 disc and prevertebral fluid collection in a rheumatoid arthritis ( ra ) patient with atlantoaxial subluxation ( aas).the patient gave consent for data concerning the case to be published . a 30-year - old woman was admitted to hospital principally complaining of severe neck pain and dysphagia over the course of one day prior . the woman was diagnosed with rheumatoid arthritis ( ra ) six years earlier , which had been well controlled with prednisolone and hydroxychloroquine and had no history of recent trauma or upper respiratory tract infection . on the day of admission , a physical examination revealed a tender cervical spine with severely limited range of motion in all directions . the pain was exacerbated by the action of swallowing and motion of the cervical spine . the mucosa of the oropharynx and nasopharynx were intact , without erythema or edema , and the patient was afebrile . laboratory tests revealed a white blood cell count of 9.0  10/mm ( 4.0 - 10.0  10 ) with a normal differential . the patient 's c - reactive protein ( crp ) level and esr had risen to 1.4 mg / dl ( 0 - 0.3 ) and 47 mm / h ( normal 0 - 22 ) , respectively from 0.03 mg / dl and esr 35 mmg / h , respectively , three months prior . 1a ) demonstrated aas and soft - tissue swelling from c1 to c4 levels without definite calcification along the anterior border of the cervical spine . the next morning , magnetic resonance imaging ( mri ) of the cervical spine ( fig . 1b - d ) revealed prominent prevertebral soft tissue swelling with fluid collection from c1 to c6 , as well as aas , a small amount of fluid collection in the atlantoaxial joint , and bony erosions in the odontoid process . in addition , no definite evidence of calcification could be seen along the lcm in the cervical spine on the initial plain radiographs and mri , and there was no osteomyelitis involving the atlas and axis on mri . possible differential diagnoses included tuberculous infection of the atlantoaxial joint , and strain of the lcm in conjunction with instability or acute retropharyngeal calcific tendinitis . on the night of admission , an additional contrast enhanced mri examination was carried out ( fig . contrast - enhanced t1-weighted mri with fat suppression showed a significant reduction in the amount of prevertebral fluid collection , with peripheral enhancement in the prevertebral region of the cervical spine . thus , the possibilities of tuberculous infection and strain could be excluded . on the third day of admission , 1 g , h ) were performed to exclude the possibility of retropharyngeal calcific tendinitis . ct scans demonstrated soft - tissue swelling and nodular calcification in the right para - midline lcm at the c4 - 5 disc ( vertical fibers of the lcm ) . on the fourth day of admission , 1i , j ) revealed a minimal amount of prevertebral fluid collection along the lcm . the patient 's symptoms resolved rapidly with pain control by non - steroidal anti - inflammatory drugs ( nsaids ) over three days , along with a reduction in the crp level ( crp 0.9 mg / dl ) . two months later , a follow - up ct of the cervical spine ( fig . 1k ) revealed a reduction in the size of calcification nodule anterior to the c4 - 5 disc . based on the successive changes , namely rapid symptom improvement and rapid reduction of the calcification nodule in the anterior border of the c4 - 5 disc , the diagnosis was acute retropharyngeal calcific tendinitis in an unusual location of an ra patient . acute retropharyngeal calcific tendinitis of the lcm is a clinical syndrome that was first described by hartley in 1964 ( 6 ) . it occurs most frequently from the third to the sixth decades of life ( 7 ) . symptoms may include mild fever , which may be secondary to inflammation of the surrounding soft tissues . laboratory data are usually normal , although inflammatory changes may be observed ( 8) . the origin of the calcium hydroxyapatite crystal deposition observed in calcific tendinitis is still not entirely clear . this disease entity seems to be associated with certain genetic and metabolic circumstances , and the possible risk factors include chronic trauma , inflammation , and tendinous degeneration ( 9 ) . therefore , a diagnostic evaluation of the more common causes of neck pain , which include but are not limited to trauma , inflammation , infection , and neoplasia , should always be performed before the possibility of calcific tendinitis is considered ( 10 ) . the lcm is located in the prevertebral space , extending from the anterior tubercle of the atlas to its inferior attachments at t3 . it consists of the superior oblique , vertical , and inferior oblique fibers ( 11 ) . the superior oblique fibers originate from the anterior tubercles of the transverse processes of c3 - 5 and insert by a tendon into the anterior tubercle on the ventral arch of the atlas . the vertical fibers arise from the bodies of c5-t3 and insert into the bodies of c2 - 4 . the inferior oblique fibers originate from the bodies of t1 - 3 and insert into the anterior tubercles of the transverse processes of c5 - 6 ( 12 ) . cervical spine radiographs usually reveal calcification anterior to the c1 - 3 bodies and the prevertebral soft tissues , and this is a typical finding of calcific tendinitis of the lcm . however , calcification may not be evident on an initial plain radiograph , as illustrated in our patient , and only diffuse soft - tissue swelling in the prevertebral c1 - 4 area may provide a clue for diagnosis . also , as illustrated in our patient , calcification may be evident on the right para - midline anterior to the c4 - 5 disc . our case shows that calcifications causing retropharyngeal calcific tendinitis can occur in the right vertical fibers of the lcm ( fig . by identifying calcifications , ct may be more helpful for diagnosis than mri , and mri may be more useful for demonstrating soft tissue edema or fluid collection , and may reveal marrow edema in the adjacent vertebrae ( 1 ) . the symptom of neck pain was important in our ra patient because the cervical spine is involved in 30 - 50% of patients with ra . the pathological lesions of ra include chronic inflammation of the synovial membrane , bone erosion , and weakening of ligament insertions . these can lead to instability , with potential impingement by aas on the spinal cord . radiographic imaging in our patient showed aas and pannus in the atlantoaxial joint with bony erosion involving the odontoid process . to our knowledge , this is the first report describing calcific tendinitis involving an unusual location of the lcm in a patient with ra and aas . acute calcific tendinitis of the lcm is a self - limiting condition that resolves spontaneously after 1 - 2 weeks . conservative treatment combined with , for example with nsaids or analgesics , and immobilization , can provide symptomatic relief . apart from the typical calcification involving the lcm , and soft - tissue swelling , rapid improvement of all symptoms with conservative treatment can confirm the diagnosis of acute calcific tendinitis of the lcm . in conclusion , we describe the first case of retropharyngeal calcific tendinitis anterior to the c4 - 5 disc , which is an unusual location , in a patient with ra and aas . we suggest that in ra patients with aas , a cervical spine ct must be performed to exclude the possibility of retropharyngeal calcific tendinitis , even though the calcification may not be seen or may be unusually located in the prevertebral space .
retropharyngeal calcific tendinitis is defined as inflammation of the longus colli muscle and is caused by the deposition of calcium hydroxyapatite crystals , which usually involves the superior oblique fibers of the longus colli muscle from c1 - 3 . 
 diagnosis is usually made by detecting amorphous calcification and prevertebral soft tissue swelling on radiograph , ct or mri . in this report 
 , we introduce a case of this disease which was misdiagnosed as a retropharyngeal tuberculous abscess , or a muscle strain of the ongus colli muscle . 
 no calcifications were visible along the vertical fibers of the longus colli muscle . 
 the lesion was located anterior to the c4 - 5 disc , in a rheumatoid arthritis patient with atlantoaxial subluxation . 
 calcific tendinitis of the longus colli muscle at this location in a rheumatoid arthritis patient has not been reported in the english literature .