Case Presentation: A 76-year-old female with hypertension, osteoarthritis, and a prior pulmonary embolism presented with two days of neck pain. She had been moving boxes and assumed she pulled a muscle but came in when the pain persisted. She endorsed subacute subjective fevers and proximal muscle pain and stiffness, which was worse in the neck and shoulders than hip girdle. She reported no jaw claudication, vision changes, or headaches and her social, surgical, and family histories were unremarkable. Her medications included amlodipine, furosemide, and vitamin D supplementation. She was afebrile, with a heart rate of 88, blood pressure of 136/61, and 16 respirations per minute. She had tenderness to palpation of neck and shoulder muscles and slightly limited neck range of motion without neck rigidity. There was no temporal pain or visible arterial swelling and vision was intact without focal neurologic findings. She had no rashes, joint swelling, or erythema. Heart and lung exams were normal. Laboratory workup was significant for a WBC 10.65 103 cells/uL, Potassium 3.3 mmol/L, Creatinine 0.89 mg/dL, Calcium 9.6 mg/dL, CRP 5.2 mg/L, ESR 103 mg/hour, ferritin 575 ug/L, CK 110 U/L (normal 26-192), vitamin D 25-OH 8ng/ml (normal 20-100), Rheumatoid factor 19 IU/ml (normal 0-14), CCP <15.62 U (normal <= 19.9), and PTH 154 pg/ml (normal 15-65). Cervical CT and MRI showed prevertebral edema from C2 through C7 and abnormal T2 STIR hyperintense signal within the interspinous ligaments at the C3-C6 level.Prednisone was started for presumed diagnosis of polymyalgia rheumatica. After two days on steroids, she had limited improvement, but the team prepared for discharge with the assumption she would slowly improve with treatment. During a ‘second look’ chart review the team discovered a history of low vitamin D and inappropriately elevated parathyroid levels for the past 10 years, likely indicating subclinical hyperparathyroidism. The CT images were further analyzed by rheumatology and neuroradiology, and were notable for a hyperintense ring around the odontoid process that was not originally mentioned. This imaging finding along with her clinical course were consistent with a diagnosis of Crowned Dens Syndrome. The patient was transitioned from steroids to NSAIDs for treatment.
Discussion: Pseudogout affects more than 200,000 Americans annually, most frequently with calcium pyrophosphate dehydrate crystal deposition in the knee. This case is important because it demonstrates that psuedogout can affect other joints. Crowned Dens Syndrome is a radiological and clinical syndrome diagnosed by the presence of calcification around the odontoid process. The disease can be asymptomatic or present with acute neck pain and is often associated with neck stiffness, fevers, elevated inflammatory markers, and nonspecific MRI findings of edema. It is thought that hyperparathyroidism leads to the development of pseudogout through inhibition of proteoglycans, which normally act to limit crystallization of calcium deposits, leading to pseudogout flares.
Conclusions: Given the rarity of this diagnosis, it can easily be misdiagnosed as a vasculitis, but is treated with NSAIDs with a more favorable side effect profile than high dose steroids. This case reminds us of the importance of recognizing rare manifestations of common diseases to avoid anchoring and confirmation bias.
