Seronegative cat-scratch disease diagnosed by PCR detection of Bartonella henselae DNA in lymph node samples.

Cat scratch disease (CSD), the typical clinical manifestation of Bartonella infections usually follows a typical benign self-limited course. Nevertheless, a variety of unusual clinical manifestations and confusing imaging features can lead to misinterpretations and render the disease a diagnostic dispute. Routine laboratory tests exhibit varying reported sensitivity and are usually unhelpful in diagnosis, as serology fails in terms of specificity and/or sensitivity. Herein we report a case of seronegative Bartonella infection presenting as symptomatic suppurative lymphadenitis with abscess formation, which was surgically drained. Diagnosis was established by PCR analysis from lymph nodes samples obtained during the procedure. PCR detection of specific DNA fragments from lymph node biopsy provides a sensitive detection of disease. The technique should be considered for patients with suspected CSD and negative serology, since serological assays exhibit low sensitivity. In ambiguous cases, surgical exploration may provide tissue for diagnosis; it is well tolerated and affords improved recovery.