Cutaneous Tuberculosis

The incidence of tuberculosis (TB) has been declining in developing countries and is rare in developed countries with the exception of immigrants, in whom an increase of the nonpulmonary forms has been reported.^"^ Immigrants in Great Britain, particularly Asians, may exhibit both common and unusual manifestations oi the disease, which may easily be overlooked. Large numbers of cases of cutaneous TB have been reported in Hong Kong, Pakistan, India, and Indonesia.''"^ In India, a higher incidence of infection has been noted in the second and third decades of life.^ Cutaneous TB is caused by Mycobacterium tuberculosis of the human, bovine and, very rarely, the avian type." Mycobacteria are slender, nonmotile, aerobic, nonsporing, weakly gram-positive rods with a waxy coating that makes them resistant to most stains; once stained, however, they are not easily decolorized, as they are acid fast. The port of entry is usually the lung but may be the tonsils or intestine. Rarely is the port of entry the skin or mucous membranes. Spreading takes place rapidly via the lymphatics to the draining lymph nodes and then by means of the blood stream."'^" Intrauterine spread to a fetus by blood or by ingestation of infected amniotic fluid has been reported.^^