title: Utility of polymerase chain reaction as a diagnostic tool in cutaneous tuberculosis.
abstract: BACKGROUND
  Differentiation of cutaneous tuberculosis from other infective granulomas of the skin is difficult due to paucity of the organisms in tissue biopsies. Polymerase chain reaction (PCR) is a newer technique to identify the DNA of Mycobacterium tuberculosis in the tissues.
  
  
  OBJECTIVE
  We examined the utility of PCR as a tool for rapid diagnosis of cutaneous tuberculosis especially in cases negative by ZN staining and culture.
  
  
  METHODS
  Twenty five random skin biopsies from patients with various types of cutaneous tuberculosis were subjected to PCR.
  
  
  RESULTS
  An overall positivity of 64% was observed, which is comparable to other series. Seventy five percent of lupus vulgaris cases, 62.2% of tuberculosis verrucosa cutis and 50% of scrofuloderma cases showed PCR positivity.
  
  
  CONCLUSIONS
  Though useful, the cost and the technique involved limit the use of PCR in developing countries like ours.
authors.affiliation: Division of Dermatology and STD, RMMC & H, RMMC, Annamalai University, Annamalai Nagar-608 002, Tamil Nadu.
authors.forename: L
authors.initials: L
authors.lastname: Padmavathy
authors.forename: L
authors.initials: L
authors.lastname: Rao
authors.forename: A
authors.initials: A
authors.lastname: Veliath