Case Presentation: A 54-year-old male with type 2 diabetes mellitus presented to the emergency department with occipital headache, neck pain, fevers, and dysuria for three days. He was diagnosed with a urinary tract infection and discharged with oral antibiotics. He was called to return to the hospital the following day because blood cultures had grown gram-positive cocci in clusters in both anaerobic and aerobic bottles within 12 hours. Upon re-admission, he was febrile to 39.4°C, with severe tenderness over his proximal cervical spine and reduced range of neck motion. Physical exam did not reveal a cardiac murmur. A neurologic exam was unremarkable. Blood and urine cultures revealed methicillin-sensitive Staphylococcus aureus, so cefazolin and gentamicin were initiated. Blood cultures cleared after five days. Given the presence of prolonged high-grade bacteremia, the patient was presumed to have endocarditis, though a transthoracic echocardiogram was negative for valvular vegetation. Because the patient’s neck pain persisted, an MRI of the spine was obtained to assess for spinal osteomyelitis or abscess. An abnormal widening of the retropharyngeal space, from the clivus to the C5-6 level was found.  Given concern for a large retropharyngeal abscess, urgent drainage was attempted via nasopharyngeal laryngoscopy, but no fluid could be collected despite multiple attempts. Subsequently, a CT scan of the neck with intravenous contrast demonstrated a pre-vertebral soft tissue swelling from the clivus through lower C5 without frank fluid collection. There was a small, amorphous calcification immediately anterior to the odontoid process. When taken together with the patient’s clinical course, these radiographic findings suggested that the patient’s neck pain was caused by retropharyngeal calcific tendonitis of the longus colli muscle, rather than a retropharyngeal abscess. He completed two weeks of NSAID therapy with improvement in his neck pain. He also completed a prolonged course of intravenous antibiotics for endocarditis.

Discussion: Retropharyngeal calcific tendonitis (RCT) is an uncommon condition caused by the deposition of calcium hydroxyapatite crystals in the longus colli muscle causing acute neck pain. Our case presented a unique diagnostic challenge in the setting of concurrent bacteremia, which does not characterize this predominantly benign condition. RCT is self-limited and usually responds to a short course of non-steroidal anti-inflammatory medications (NSAIDs). This condition is often mistaken for a retropharyngeal abscess; thus, a correct diagnosis is critical in avoiding unnecessary invasive procedures, such as incision and drainage. 

Conclusions: RCT can be mistaken for retropharyngeal abscess, and case reports have documented this occurrence. Without need for invasive diagnostic or therapeutic procedures, RCT should always be considered in cases of acute neck pain with radiographic retropharyngeal abnormalities.