For a group of clinicians in Australia, the diagnosis of meningococcal arthritis was “straightforward” except for abnormal serum total protein, anemia, and immunoglobulin results, which suggested their patient might have a hematological disorder such as myeloma.
The patient came to the hospital after 4 days of worsening knee and arm pain so severe he could not stand. His knees and both wrists showed swelling but no palpable lymphadenopathy or hepatosplenomegaly. The patient’s medical history showed he was taking no regular medications.
Joint aspiration grew Neisseria meningitidis. The patient’s blood tests showed hemoglobin 126 g/dL, white blood cell count 15.3 x 109/L, an unusually high total protein level (100 g/L), and an IgM kappa paraprotein band of 45 g/L on protein electrophoresis. A computed tomography scan showed widespread lymphadenopathy, hepatosplenomegaly, and multilevel thoracic vertebral collapse. A bone marrow biopsy showed evidence of a lymphocytic infiltrate, with lymphoplasmacytoid differentiation.
The histology best fitted a diagnosis of nodal marginal zone lymphoma with plasmacytic differentiation, the clinicians say. Having ruled out other possibilities, they settled on non-Hodgkin lymphoma.
Initially, the suspicion was that the patient had septic arthritis due to Staphylococcus aureus (the most common organism isolated in septic arthritis), and he was given piperacillin/tazobactam. That was changed to flucloxacillin and then to ceftriaxone after the result of N meningitidis. The patient also was treated with rituximab and bendamustine for the lymphoma with a complete remission.
Meningococcal infection presenting as septic arthritis in the case of invasive meningococcemia is rare, the clinicians say, but primary meningococcal arthritis is even rarer. The case highlights the important aspect that “diagnosis of one condition can lead to diagnosis of another”—in this case, the lymphoma-weakened immune system led to the symptoms of polyarthropathy and the diagnosis of primary meningococcal arthritis. The clinicians also cited a case of a patient who presented with meningococcal meningitis and arthritis who was found to have an underlying Waldenström disease, and a patient whose HIV was diagnosed again after the patient presented with meningococcal arthritis symptoms.
The clinicans say such cases underscore the importance of screening for an underlying impaired immune response in patients presenting with rare conditions such as meningococcal arthritis.