[Acquired reactive perforating collagenosis: report of two cases].

Acquired reactive perforating collagenosis is a perforating dermatosis characterized by transepidermal elimination of collagen. It is frequently associated to diabetes mellitus and chronic renal insufficiency, but it is also related to other systemic diseases. The lesions tend to resolve once the underlying condition is treated.

[Skin biopsy for the diagnosis of nervous system diseases].

Skin biopsy is a powerful diagnostic tool in dermatology. Its use has been extended to other medical specialties, allowing the diagnosis of several diseases that previously required complex and high risk diagnostic procedures. Skin contains numerous cell types, including blood vessels and peripheral nerves and represents a window to the systemic circulation and nervous system.