"Papulo-necrotic and papulo-squamous tuberculides (Boeck) are small, round, slightly raised, rather hard, flat papules ranging in size from a pinhead to a millet seed, of red to reddish-brown to livid brown color, often presenting on their surface a small dry crust which is easily removed, leaving a whitish, central depression with occasionally a small bleeding point in its center. If put on the stretch they have a glistening appearance." (From Hamburger's1 description). The lesions generally appear in crops and heal spontaneously in from four to eight weeks.
Before going into a general discussion it will probably be of interest briefly to review the history of the relation of these and other tuberculous lesions to tuberculosis. Before Koch's discovery of the tubercle bacillus only the ulcerative lesions of certain types were classified as tuberculosis of the skin, although it was noted that individuals with tuberculosis were prone to certain
WRONKER BM. PAPULO-NECROTIC TUBERCULIDES IN INFANTS. Am J Dis Child. 1913;V(6):447-456. doi:10.1001/archpedi.1913.04100300024002