title: Syphilitic orchitis mimicking a testicular tumor in a clinically occult HIV-infected young man: a case report with emphasis on a challenging pathological diagnosis.
abstract: BACKGROUND
  Syphilitic orchitis is a rare manifestation of gumma in tertiary syphilis, microscopically typically characterized by multiple discrete granulomas with central necrosis and peripheral fibrosis. We report a case of syphilitic orchitis mimicking a testicular tumor with atypical histological features.
  
  
  METHODS
  A 33-year-old clinically occult HIV-infected man had a testicular tumor. A radical orchiectomy was performed, and a histological examination showed an acute and chronic interstitial inflammatory lesion as well as spindle cell proliferation, without typical gumma formation, necessitating the differential diagnosis having to be made from a panel of etiological factors. Syphilitic orchitis was confirmed by both an immunohistochemical study and PCR testing for the Treponema pallidum DNA polymerase I gene using paraffin-embedded tissues. However, serology tests, including both the Venereal Disease Research Laboratory (VDRL) test and Treponema pallidum partical agglutination (TTPA), demonstrated false-negative results.
  
  
  CONCLUSIONS
  Syphilitic orchitis may present atypical and unusual histological features, and should be included in the differential diagnoses of nonspecific interstitial inflammatory lesions of the testes by pathologists, especially in immunocompromised patients.
authors.affiliation: Department of Pathology, Taipei Medical University Hospital, Taipei, Taiwan. poohlover0517@gamil.com.
authors.forename: Chia-Ying
authors.initials: CY
authors.lastname: Chu
authors.affiliation: Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. 1047@tmu.edu.tw.|Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan. 1047@tmu.edu.tw.
authors.forename: Wei-Yu
authors.initials: WY
authors.lastname: Chen
authors.affiliation: Department of Urology, Taipei Medical University Hospital, Taipei, Taiwan. yehsd@tmu.edu.tw.
authors.forename: Shauh-Der
authors.initials: SD
authors.lastname: Yeh
authors.affiliation: Department of Radiology, Taipei Medical University Hospital, 250 Wu Hsing Street, Taipei, 110, Taiwan. ping9685@gmail.com.
authors.forename: Huey-Min
authors.initials: HM
authors.lastname: Yeh
authors.affiliation: Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan. ccllfang@tmu.edu.tw.|Department of Pathology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan. ccllfang@tmu.edu.tw.
authors.forename: Chia-Lang
authors.initials: CL
authors.lastname: Fang
mesh_terms: D017088:AIDS-Related Opportunistic Infections / Q000276:immunology / Q000382:microbiology / Q000473:pathology* / Q000601:surgery; D000328:Adult; D001431:Bacteriological Techniques; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D015658:HIV Infections / Q000175:diagnosis / Q000276:immunology*; D006801:Humans; D016867:Immunocompromised Host; D007150:Immunohistochemistry; D008297:Male; D009919:Orchiectomy; D009920:Orchitis / Q000276:immunology / Q000382:microbiology / Q000473:pathology* / Q000601:surgery; D011237:Predictive Value of Tests; D013587:Syphilis / Q000276:immunology / Q000382:microbiology / Q000473:pathology* / Q000601:surgery; D013736:Testicular Neoplasms / Q000473:pathology*; D014057:Tomography, X-Ray Computed; D014210:Treponema pallidum / Q000302:isolation & purification*