Aplasia cutis congenita with precancerous transformation - the first case.Why do these scars never develop invasive tumors?

The term aplasia cutis congenita characterizes a heterogeneous group of dis eases which have in common a focal absence of the skin. The defect may be l imited to the epidermis but often involves the full thickness of the skin i ncluding the underlying bone. At birth the lesions present as erosive patch es and they heal rather rapidly with a residual scar. Although more than 20 0 publications on aplasia cutis congenita have appeared in the medical lite rature between 1966 and 1999, surprisingly no case of malignant degeneratio n has been described. We observed a 58-year-old male patient with aplasia cutis congenita who dev eloped crusted changes within the scar over the past 10 years. Repeated bio psies over the years have always documented a precancerous lesion without s olar elastosis. Invasion has never been observed in this patient. We hypothesize that for invasive malignancies dermal-epidermal interactions are necessary. Such a cell to cell communication seems to be impossible in patients with aplasia cutis congenita, as the dermal-epidermal unit is not developed. Aplasia cutis congenita might serve as an interesting model for further investigations on the importance of epidermal-dermal interactions.