Case report: crowned dens syndrome in a patient with seronegative rheumatoid arthritis.

Chondrocalcinosis (CC) is the one of the most common crystal pyrophosphate disease associated arthritis in the elderly. It has been shown to coexist with seronegative and seropositive rheumatoid arthritis (RA), yet mostly with seronegative RA. Among the localisation of CC, the deposition in the ligaments surrounding the odontoid process may remain asymptomatic for years or may lead to and acute severe symptomatology, which may mimic several clinical illnesses among which meningitis (fever, severe pain, acute phase reactants). This is called the 'crowned dens syndrome (CDS)', which has been reported to represent an important percentage of acute neck pain needing hospital admission in neurosurgery units. In this case, the rapid demonstration of 'crowned dens' through CT scan may allow to avoid lumbar puncture and cerebrospinal fluid examination. The coexistence of RA and CDS is very rare, and rarely reported in the literature, yet it may represent a clinical challenge. We describe here one case that while on therapy with methotrexate (MTX) and naproxen (NPX) had an acute neck pain, and peripheral arthritis flare, that responded well to colchicine given along with MTX and NPX.