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Shortly after the biopsies were performed, the child's father was available to provide additional history. The father was scratched by the family's kitten shortly after its acquisition 1 month before. He was given penicillin prophylaxis. He developed a fever and axillary lymphadenopathy 1 week later, a course of illness that suggested cat-scratch disease.
Pathologic specimens demonstrated small, rodlike organisms on Warthin-Starry staining of the lymph node (Figure 3B, inset). The B henselaegenome was detected by polymerase chain reaction testing of the muscle tissue. Convalescent B henselaeserology remained at the same titers (IgM < 1:16; IgG, 1:128) as during the acute phase of the illness. Cat-scratch disease is a well-known cause of fever and lymphadenopathy in children. The causative agent, B henselae, is a pleomorphic, aerobic, gram-negative bacterium commonly found in the oral flora of cats and kittens as well as other animals.1
A, Histologic section of the lymph node biopsy specimen showing effacement of normal lymph node architecture and replacement by granulomatous inflammation characterized by an outer rim of small lymphocytes and collections of epithelioid histiocytes with a pale eosinophilic appearance surrounding areas of suppurative necrosis (arrows) (hematoxylin-eosin staining, original magnification ×100). B, Histologic section of the needle biopsy specimen of left pelvic tissue showing a dense mixed inflammatory infiltrate composed of lymphocytes (far right) and collections of palisading epithelioid histiocytes (white arrows) surrounding areas of suppurative necrosis (black arrows) (hematoxylin-eosin staining, original magnification ×100). Inset, Warthin-Starry silver staining was performed and showed a few small rod-shaped organisms (arrow) (original magnification ×1000).
Lymphadenopathy or lymphadenitis develops in regional lymph nodes following inoculation by a cat scratch or bite. Bacterial spread can occur through contiguous or hematogenous routes. Suppurative complications of B henselae, while uncommon, have been described in the literature.2- 5Bone infection occurs in 0.17% to 0.27% of known cases of cat-scratch disease; the pelvic girdle is the second-most-common site of osteomyelitis after the vertebral column. Approximately 12% of patients with B henselaeosteomyelitis have concomitant lymphadenopathy.6Myalgia is a common complaint in children with cat-scratch disease,7though myositis is infrequently described. Our patient had significant myositis visualized on magnetic resonance imaging adjacent to the area of osteomyelitis.
Bartonellaserology is the most commonly used diagnostic test, with a sensitivity as high as 88% and a specificity of 97%, compared with patients with a clinical presentation consistent with cat-scratch disease and one other positive diagnostic test result (culture, skin testing, or polymerase chain reaction). Acute-phase titers are normal in as many as 75% of infected patients and should be repeated in the convalescent phase for diagnosis. Bartonellapolymerase chain reaction has become an added tool in the diagnosis of this elusive infection. The literature indicates that although sensitivity of the assay may be low (43%-76%), specificity is high, even reaching 100% compared with combined clinical, histologic, and serologic evidence.8
In the immunocompetent host, cat-scratch disease is a self-limited process. Treatment of suppurative B henselaeinfections has not been adequately evaluated. One review of 47 cases of osteomyelitis caused by B henselaesuggested that the prognosis for recovery is excellent irrespective of antimicrobial selection.6
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Correspondence:Eric J. Haas, MD, Pediatrics A, Soroka University Hospital, Beersheva 84101, Israel (firstname.lastname@example.org).
Accepted for Publication:August 23, 2008.
Author Contributions:Study concept and design: Haas and Ernst. Acquisition of data: Ernst. Analysis and interpretation of data: Ernst. Drafting of the manuscript: Haas and Ernst. Critical revision of the manuscript for important intellectual content: Ernst. Administrative, technical, and material support: Haas and Ernst. Study supervision: Ernst.
Financial Disclosure:None reported.
Picture of the Month—Diagnosis. Arch Pediatr Adolesc Med. 2009;163(1):86. doi:10.1001/archpediatrics.2008.514-b