Musculoskeletal manifestations of cat scratch disease.

Background: Musculoskeletal manifestations (MMs) are considered to be rare in cat scratch disease (CSD) and are not well characterized. We aimed to study MMs of CSD.

Methods: A surveillance study performed over 11 years identified patients with CSD on the basis of compatible clinical presentation and confirmatory serological test or PCR results for Bartonella henselae. Patients with CSD who had MMs (i.e., myalgia, arthritis, arthralgia, tendinitis, osteomyelitis, and neuralgia) were compared with patients with CSD who did not have MMs (control subjects).

Results: Of 913 patients with CSD, 96 (10.5%) had MMs. Myalgia (in 53 patients [5.8%]) was often severe, with a median duration of 4 weeks (range, 1-26 weeks). Arthropathy (arthralgia and/or arthritis; in 50 patients [5.5%]) occurred mainly in the medium and large joints and was classified as moderate or severe in 26 patients, with a median duration of 5.5 weeks (range, 1-240 weeks). In 7 patients, symptoms persisted for >or=1 year; 5 developed chronic disease. Tendinitis, neuralgia, and osteomyelitis occurred in 7, 4, and 2 patients, respectively. Patients with MMs were significantly older than patients in the control group (median age, 31.5 years vs. 15.0 years). In multivariate analysis, age >20 years was associated with having any MM (relative risk [RR], 4.96; 95% confidence interval [CI], 2.79-8.8), myalgia (RR, 4.69; 95% CI, 2.22-9.88), and arthropathy (RR, 11.0; 95% CI, 4.3-28.2). Arthropathy was also associated with female sex (RR, 1.89; 95% CI, 1.01-3.52) and erythema nodosum (RR, 4.07; 95% CI, 1.38-12.02).

Conclusions: MMs of CSD are more common than previously thought and affect one-tenth of patients with CSD. MMs occur mostly in patients aged >20 years and may be severe and prolonged. Osteomyelitis, the most well known MM of CSD is, in fact, the rarest.