Cases typically follow a prolonged and relapsing course lasting years, though spontaneous resolution has been reported. Significant varioliform scarring is a sequela and progression to lupus vulgaris is reported to occur. There have also been reports of an association with Takayasu s arteritis of the aortic arch. Females seem to be at slightly increased risk for developing this disorder. The characteristic lesions are small erythematous inflammatory papules that undergo central ulceration and heal spontaneously within weeks leaving a varioliform scar.
Lesions arise in symmetric crops typically with an acral predilection.
Characteristically, lesions develop over the extensor surfaces, particularly the knees, elbows and dorsum of the hands and feet, though widespread involvement may be present. New lesions form as older lesions resolve giving the eruption a polymorphous appearance. Oral lesions have not been reported to date. Lesions of PNT have been reported to coexist with lesions of erythema induratum. In several reports both types of lesions resolved with appropriate anti-tuberculosis treatment.