title: Compressive spinal epidural mass caused by Propionibacterium acnes.
abstract: Propionibacterium acnes is a gram-positive and facultative anaerobe bacillus that is found within sebaceous follicles of the human skin and recognized as a cause of infections after spinal surgery. To our knowledge, there has been no previously reported case of symptomatic compressive chronic inflammatory epidural mass caused by P. acnes in a patient with no prior spinal procedures.
  
  
  
  This study aimed to describe a case of primary spinal infection by P. acnes.
  
  
  
  This study is a case report of a condition not previously described in the literature.
  
  
  
  We present the history, physical examination, laboratory, radiographic, and histopathologic findings of a chronic inflammatory epidural mass caused by P. acnes in an immunocompetent adult male with no history of spinal surgery.
  
  
  
  A 51-year-old man presented to our clinic with sudden onset bilateral lower extremity weakness, inability to ambulate, and urinary retention. His past clinical history was remarkable only for hernia and left knee surgery but no spinal surgery. A year earlier, he had an infected draining abscess of the right axilla that was successfully managed medically. At presentation, his serum erythrocyte sedimentation rate and C-reactive protein were moderately elevated. Pan-spine magnetic resonance imaging was notable for a circumferential epidural mass from C5 to T6. He underwent emergent decompression; the mass was removed and sent for culture and pathologic evaluation. Cultures from all three specimens collected during surgery grew P. acnes, and the patient was successfully managed on intravenous ceftriaxone, while pathology revealed a chronic inflammatory reactive process.
  
  
  
  This is the first reported case of a primary spinal mass with chronic inflammatory features caused by P. acnes. In cases of epidural mass of unknown origin, both pathologic specimens and cultures should be obtained as slow-growing organisms may mimic oncologic processes.
authors.affiliation: Warren Alpert Medical School of Brown University, 222 Richmond St, Providence, RI 02903, USA. Electronic address: austin_youngsoo_ha@brown.edu.
authors.forename: Austin Y
authors.initials: AY
authors.lastname: Ha
authors.affiliation: Department of Orthopaedics, Warren Alpert Medical School of Brown University, 593 Eddy St, Providence, RI 02903, USA.
authors.forename: J Mason
authors.initials: JM
authors.lastname: DePasse
authors.affiliation: Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, 593 Eddy St, Providence, RI 02903, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Piskorski
authors.affiliation: Department of Pathology and Laboratory Medicine, Warren Alpert Medical School of Brown University, 593 Eddy St, Providence, RI 02903, USA.
authors.forename: Diana O
authors.initials: DO
authors.lastname: Treaba
authors.affiliation: Department of Immunology, Warren Alpert Medical School of Brown University, 593 Eddy St, Providence, RI 02903, USA.
authors.forename: Erna M
authors.initials: EM
authors.lastname: Kojic
authors.affiliation: Department of Orthopaedics, Division of Spine Surgery-Adult Spinal Deformity Service, Warren Alpert Medical School of Brown University, 593 Eddy St, Providence, RI 02903, USA.
authors.forename: Alan H
authors.initials: AH
authors.lastname: Daniels
mesh_terms: D001424:Bacterial Infections / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology*; D004824:Epidural Space / Q000382:microbiology* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011425:Propionibacterium acnes / Q000472:pathogenicity*; D013117:Spinal Cord Compression / Q000000981:diagnostic imaging / Q000382:microbiology / Q000473:pathology*
keywords: Compression; Epidural abscess; Laminectomy; Primary spinal infection; Propionibacterium acnes; Spinal cord