All dermatologists are aware of the great progress that has been made in recent years in our knowledge of cutaneous tuberculosis. We have kept abreast of the advances with the knowledge of tuberculosis elsewhere and have followed the research in related fields. We have attempted to apply the new facts as each was established to what was known about cutaneous tuberculosis, but despite our considerable present knowledge, despite all the advances in the fields of allergy and immunology, we have been unable to find an explanation for the great variance in the morphologic aspects of the various tuberculoderms as we know them today. The finding of the tubercle bacillus in lupus vulgaris lesions, both by culture and inoculation, disclosed that this cutaneous disease is in general tuberculous. This was a great advance, but it did not explain why in certain tuberculous patients there should develop such a slow, almost benign,