Abstract Background Bartonella henselae infection classically presents as cat-scratch disease with regional lymphadenopathy. However, its atypical presentations, such as occult fever and isolated mediastinal lymphadenopathy, can perfectly mimic malignancy, posing a significant diagnostic challenge. Targeted next-generation sequencing (tNGS) offers a powerful and unbiased method for pathogen detection, but its clinical diagnostic rate is highly dependent on optimal sample acquisition, a principle that is crucial in clinical practice but is often overlooked. Method We present two illustrative cases where tNGS plays a important role in diagnosis, highlighting the impact of sampling site.Case 1 A 34-year-old woman underwent a PET/CT scan due to recurrent high fever. The results showed a mass with increased FDG uptake in the right hilum, multiple lymph nodes with increased FDG uptake (mediastinum, abdomen), and hepatic hilum. There were also lesions in the liver, and lymphoma was highly suspected. Subsequently, an endobronchial ultrasound-guided transbronchial needle aspiration biopsy (EBUS-TBNA) was performed. Although histopathological examination failed to confirm a malignant tumor, tNGS sequencing of needle aspiration fluid ultimately identified Bartonella henselae with 3654 unique reads. Case 2 A 48-year-old male patient presented with recurrent nocturnal fever and tenderness of the axillary lymph nodes. A chest CT revealed incidental pulmonary nodules. His condition proved refractory to multiple broad-spectrum antibiotic regimens. Pathological examination of the excised lymph node biopsy showed granulomatous inflammation with microabscess formation; special staining and Mycobacterium tuberculosis PCR test results were both negative. Subsequently, tNGS analysis of the lymph node aspiration fluid was positive for Bartonella henselae with 143014 unique reads, whereas tNGS of the bronchoalveolar lavage fluid (BALF) was negative.Both patients were treated with doxycycline, leading to rapid resolution of symptoms and resolution of the lymphadenopathy on clinical and radiologic follow-up. Conclusions This case series powerfully illustrates the capacity of tNGS to resolve diagnostic dilemmas in atypical Bartonellosis, thereby preventing misdiagnosis and guiding curative therapy. Case 1 highlights the advantages of combining EBUS-TBNA with tNGS: this minimally invasive approach can clearly diagnose clinical manifestations similar to lymphoma and avoid invasive surgery. Furthermore, the significant differences in tNGS test results from different sites in the same patient (Case 2) provide irrefutable evidence for the principle of precise sampling: by accurately performing tNGS testing on samples from the primary site of infection, the diagnostic rate can be maximized. For clinicians, strategic sampling of primary infected tissue is key to fully realizing the potential of tNGS. This abstract is funded by: Science and Technology Program of Guangzhou (No.2025A04J4090, NO.2025A04J4104)
Su et al. (Fri,) studied this question.