INTRODUCTION

My cobacterium tuberculosis is the causative agent of tuberculosis (TB). Its a tubercle bacillus.TB is an ancient disease.

1 of 3 individuals on this planet is infected with tubercle bacillus, the incidence of cutaneous TB appears low.

In areas such as India and china,where TB prevalence is high, cutaneous manifestations of TB(overt infection or tuberculin) are found in less than 0.1% of individuals seen in dermatology clinic.

  In a 10 year(1983-1992)retrospective survey of patients seen in governmental dermatology clinics in Hong kong, the detected incidence of cutaneous TB among patient was 179 per 267,089(0.07%).Among patients with cutaneous TB,15% had classic cutaneous TB(approximately 5% of each of lupus vulgaris,TB verrucosa cutis and scrofuloderma) and 85% had tuberculids.