Cat scratch disease with fever and lymphadenopathy without definite cat exposure diagnosed via tissue metagenomic next-generation sequencing technology: a case report.

BACKGROUND: Cat scratch disease (CSD), a disease caused by Bartonella henselae (B. henselae), is often associated with exposure to cats. However, in rare cases, a history of cat exposure is absent, and thus achieving a definitive diagnosis may be challenging. Metagenomic next-generation sequencing (mNGS) is a relatively new technology that can analyze pathogens without introducing inherent biases. In this report, we describe a case of CSD diagnosed via mNGS, which supports the use of mNGS in identifying rare types of pathogenic infection.

CASE DESCRIPTION: A 54-year-old male exhibited fever and headache of unknown cause, with a history of working at a chicken farm and no clear cat exposure. Routine antibiotic treatment for infection was ineffective. Lymph node biopsy demonstrated granulomas accompanied by chronic suppurative inflammation and abscess formation. A biopsy sample from the parotid lymph node was subjected to mNGS, which revealed the presence of B. henselae and led to a subsequent diagnosis of CSD. After treatment with azithromycin, the patient recovered and was discharged. At the 3-month telephone follow-up, the patient was asymptomatic.

CONCLUSIONS: CSD in patients with prolonged fever plus culture-negative granulomatous lymphadenopathy or similar compatible findings, even when the exposure history is atypical，and mNGS, as an effective examination method, can aid in arriving at a definitive diagnosis.