However, recent studies have shown that bilateral idiopathic adrenal hyperplasia is the cause in up to 70 of cases.

The walls of the epidermal cells of the above ground parts of plants contain cutin, and are covered with a cuticle.

Epidermal nerve fiber density testing (ENFD) is a more recently developed neuropathology test in which a punch skin biopsy is taken to identify small fiber neuropathies by analyzing the nerve fibers of the skin.