Perforating necrobiosis lipoidica is a secondary perforating disease with necrobiotic collagen elimination through the epidermis in diabetic patients. Lesions are very similar to classic necrobiosis lipoidica but in the former there are keratotic plugs over the raised borders of the atrophic yellow plaques. It is explained by necrotic collagen on upper dermis causing inflammation and breaking on through the hair follicle wall or abnormal channels connecting dermis with the outside. In spite of its low frequency, this manuscript highlights the first case reported in Colombia, the 19 th case worldwide.

Perforating necrobiosislipoidica is a secondary perforating disease with necrobiotic collagen elimination through the epidermis in diabetic patients. Lesions are very similar to classic necrobiosislipoidica but in the former there are keratotic plugs over the raised borders of the atrophic yellow plaques. It is explained by necrotic collagen on upper dermis causing inflammation and breaking on through the hair follicle wall or abnormal channels connecting dermis with the outside. In spite of its low frequency, this manuscript highlights the first case reported in Colombia, the 19th case worldwide.

Chronic inflammation due to periapical abscess can drain into the mouth or outside of the skin through sinus tract. In this last, it may be difficult to differentiate the opening of the fistula from primary skin conditions by the general physician who wrongly refers patients to dermatology, being a main issue of dentist.