Progressive form of cutaneous tuberculosis occurring in a person with a moderate or high degree of immunity. The pathogen may reach the skin by exogenous inoculation, via the blood or lymph from a tuberculous internal organ, or by direct extension from underlying infected glands or joints. The characteristic lesion is a reddish-brown plaque, composed of nodules which show an ‘apple-jelly’ colour when pressed with a glass spatula (diascopy). The disease often affects the face leading to disfigurement due to the destructive skin lesions. It is twice as common in women as in men.
Lupus vulgaris, Tuberculosis cutis luposa