title: Clinical and histopathological features of cutaneous nontuberculous mycobacterial infection: a review of 13 cases.
abstract: BACKGROUND
  The incidence of cutaneous nontuberculous mycobacterial (NTM) infection has increased in recent decades because of widespread use of immunosuppressive therapy and better detection methods. The histopathology of cutaneous NTM infection is not pathognomic and the organisms are slow and difficult to culture, making diagnosis challenging.
  
  
  METHODS
  We reviewed the clinical and histopathological features of 13 cases of cutaneous NTM infection, and performed panmycobacterial polymerase chain reaction (PCR) on the paraffin blocks.
  
  
  RESULTS
  The immunocompetent patients presented with localized lesions on the extremities, whereas the immunocompromised patients presented with disseminated cutaneous lesions. The histopathology in immunocompetent patients was characterized by pseudoepitheliomatous epidermal hyperplasia, intraepithelial abscesses, transepidermal elimination and dermal granulomatous inflammation accompanied by necrosis and suppuration. The immunocompromised patients showed suppurative inflammation with little granuloma formation and numerous acid-fast bacilli. Paraffin block PCR was positive in 4 of 13 cases (31%), whereas culture was positive in 11 of 13 cases (85%).
  
  
  CONCLUSIONS
  The aforementioned histological features should help in diagnosing cutaneous NTM infection when combined with clinical and microbiological correlation. In our study, we did not find paraffin block PCR to be superior to conventional culture in detecting cutaneous NTM infection.
authors.affiliation: Department of Anatomical Pathology, Liverpool Hospital, Liverpool, Australia.
authors.forename: Jing Jing
authors.identifier: http://orcid.org/0000-0002-1658-0375
authors.initials: JJ
authors.lastname: Li
authors.affiliation: Department of Microbiology and Infectious diseases, Liverpool Hospital, Liverpool, Australia.
authors.forename: Rohan
authors.initials: R
authors.lastname: Beresford
authors.affiliation: Mycobacterium Reference Laboratory Victorian Infectious Diseases Reference Laboratory, North Melbourne, Australia.
authors.forename: Janet
authors.initials: J
authors.lastname: Fyfe
authors.affiliation: Department of Anatomical Pathology, Liverpool Hospital, Liverpool, Australia.
authors.forename: Christopher
authors.initials: C
authors.lastname: Henderson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D020405:Dermis / Q000382:microbiology / Q000473:pathology*; D004817:Epidermis / Q000382:microbiology / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009165:Mycobacterium Infections, Nontuberculous / Q000382:microbiology / Q000473:pathology*; D009170:Nontuberculous Mycobacteria; D017192:Skin Diseases, Bacterial / Q000382:microbiology / Q000473:pathology*
keywords: granuloma; histology; mycobacteria; polymerase chain reaction; skin