Retrospective study and Diagnostic Immunohistochemistry of Lymph Nodes in Suspected Cat Scratch Disease Cases in Taiwan, 2001-2004

Bartonella henselae is the causative agent of cat scratch diseases (CSD), which usually manifests as acute regional lymphadenopathy. From January 2001 through December 2004, 377 sera from 352 reportable CSD cases were examined by indirect fluorescence antibody assay (IFA). Ninety-nine patients were seropositive to B. henselae and which contributed to 28.1% seroprevalence in CSD suspected patients. Epidemiological features, like geographic and seasonal distribution or clinical presenting symptom were analyzed. There were 50.5% (50/99) of CSD seropositive patients were lived in north of Taiwan and 35.4% (35/99) of them were occurring in summer. The retrospective study of 152 CSD suspected cases demonstrated the seropositive results associated with cat contact, axillary and elbow lymphadenopathy. Immunohistologic studies for localization of B. henselae in collected 16 lymph nodes biopsies and 2 skin biopsies out of 352 patients were carried out by polyclonal antibody-based immunohistochemistry (IHC) and polymerase chain reaction (PCR) for comparing. IHC demonstrated the presence of the organism in intracellular location within granulomatous lesions in lymph node tissues. Ten lymph nodes from CSD suspected patients showed IHC positive and 3 of them were seronegative. The PCR results showed high sensitivity of 93.3% (14/15) cases positive. Immunohistochemistry can contribute to the etiologic diagnosis of Bartonella lymphadenopathy when serology and molecular techniques are not available.