A 76-year-old woman with a history of ischaemic heart disease, diagnosed with seronegative rheumatoid arthritis in 1992 due to chronic, symmetrical, erosive polyarthritis which fulfilled five of the criteria of the American College of Rheumatology. Chloroquine and parenteral methotrexate had been used as background medication. In 2000 she underwent total right knee arthroplasty with a satisfactory result. In 2002 she developed normocytic anaemia, fatigue, sensorimotor peripheral neuropathy and splenomegaly. A haematological study revealed a monoclonal IgM component of 3.1 g/dl and after a bone marrow biopsy she was diagnosed with Waldenström's macroglobulinemia. Since the patient remained stable and oligosymptomatic with low doses of prednisone (7.5 mg/day) and oral methotrexate (7.5 mg/week), the haematology department decided to maintain a wait-and-see attitude, deferring therapy with alkylating agents or nucleoside analogues.
During the first three days of August 2005, he presented with self-limited febrile diarrhoea. After a week's improvement, he began to experience fever, pain, swelling and progressive limitation of mobility in the right knee, symptoms that persisted and led to consultation and admission to our centre on 25 August.
Examination revealed an axillary temperature of 37.5ºC, swelling and tension effusion in the right knee, patchy hypoaesthesia in the lower limbs and abolition of the Achilles reflexes. Arthrocentesis revealed a cream-coloured purulent fluid with 75,000 leukocytes/mm3 (> 95% polymorphonuclear). Gram stain failed to visualise microorganisms, but aerobic cultures recovered L. monocytogenes sensitive to penicillin, ampicillin, co-trimoxazole and rifampicin. ESR was 120 mm/1 hour. C-reactive protein: 51.7 mg/L. CBC showed 6.5 x 109 leukocytes/L (47% neutrophils, 25% lymphocytes, 14% monocytes), Hb: 99 g/L, haematocrit: 28.7 L/L, platelets: 442 x 109/L. Immuglobulin levels: IgA (25 mg/dl), IgG (405 mg/dl), IgM (2300 mg/dl; VN < 230); light chains: lambda (44 mg/dl; VN: 90-210), kappa (276 mg/dl; VN 170-370). The following parameters were normal or negative: biochemistry (glucose, creatinine, urea, total cholesterol, triglycerides, lacticodehydrogenase, creatinine kinase, transaminases, bilirubin, alkaline phosphatase, gamma-glutamyltranspeptidase, calcium, phosphorus, sodium, potassium and chloride), urinalysis, serology for Salmonella, Shigella and Yersinia, complement dosage (C3 and C4) and antinuclear antibodies. Rheumatoid factor by latex was 54 IU/ml.
Chest X-ray showed no abnormalities. X-ray of the right knee showed periprosthetic radiolucencies. Abdominal ultrasound showed signs of hepatic steatosis and mild splenomegaly. In addition to drainage and saline lavage of the joint, 2 g of ampicillin every 6 h and gentamicin (3 mg/kg/8 hours; maintaining a concentration between 4 and 9 mg/ml) were administered intravenously for 5 weeks. At the time of writing this clinical note, three months after discharge from hospital, the patient is progressing favourably and is receiving treatment with co-trimoxazole and rifampicin, which will be continued for a total of 6 months.