Onycholysis, loose nail.
An Onycholysis nail becomes detached from its bed at base and/or side, creating a space under nail that accumulates dirt. Air under nail may cause grey-white colour but can vary from yellow to brown. In psoriasis can see yellowish-brown margin between margin between normal nail (pink) and detached parts (white). If Pseudomonas aeruginosa grows underneath nail, then green colour. When nail bed separation begins in middle of nail then see ‘oil spot’ or ‘salmon-patch’ form. Causes – idiopathic or inherited, systemic disease, e.g. thyrotoxicosis, skin disease, e.g. psoriasis or local causes, e.g. trauma or chemicals.