First reported case of Lawsonella clevelandensis brain abscess in the setting of invasive cutaneous squamous cell carcinoma identified via bedside stereotactic aspiration: illustrative case.

backgroundBrain abscesses associated with malignant skull base invasion pose unique diagnostic and management challenges for neurosurgeons, particularly when routine cultures remain negative. The authors report the first documented intracranial infection caused by Lawsonella clevelandensis, a recently described anaerobe that mimics Nocardia or Mycobacterium sp., diagnosed using bedside stereotactic biopsy as well as metagenomic next-generation sequencing. OBSERVATIONS: A 74-year-old woman with recurrent, locally invasive facial squamous cell carcinoma presented with recent-onset shaking of her lower extremity and a large right frontal mass extending through the calvarium and orbit. Imaging revealed ring-enhancing lesions consistent with abscess. Bedside stereotactic biopsy and drainage were performed, and metagenomic sequencing identified L. clevelandensis. Antibiotics were narrowed to ceftriaxone and metronidazole, stabilizing her condition, although repeat drainage was required for radiographic progression. She subsequently underwent multidisciplinary skull base resection and reconstruction, with operative cultures isolating Enterococcus faecium but no further Lawsonella sp. LESSONS: This case represents the first documented intracranial L. clevelandensis infection and demonstrates the diagnostic value of molecular sequencing in culture-negative brain abscesses. It also highlights bedside stereotactic biopsy and drainage as a safe, minimally invasive strategy for managing intracranial infection in medically complex patients. https://thejns.org/doi/10.3171/CASE25887.