Cutaneous cysts: a plea for systematic analysis.

So-called cutaneous cysts are extremely frequent tumours that could need surgical attention. Most of the time, due to their quite pathognomonic clinical presentation and indolent course, they are simply enucleated. Often, the clinical diagnosis is easily confirmed at surgery by the typical appearance of a cystic formation filled with a creamy fluid. It is frequent for such "typical" lesions to escape histological investigation following removal. However, some mimicking lesions could also be found as "cutaneous cysts" and have quite different prognoses. This paper present five patients with such lesions, three basal cell carcinomas, one benign proliferating trichilemmal cyst and a malignant proliferating trichilemmal cyst. None of the lesions was clinically distinguishable from a classical epidermis cyst.