Other risk factors include perspiring heavily, being in a humid or moist environment, psoriasis, wearing socks and shoes that hinder ventilation and do not absorb perspiration, going barefoot in damp public places such as swimming pools, gyms and shower rooms, having athletes foot (tinea pedis), minor skin or nail injury, damaged nail, or other infection, and having diabetes, circulation problems, which may also lead to lower peripheral temperatures on hands and feet, or a weakened immune system. Diagnosis
The diagnosis is generally suspected based on the appearance and confirmed by laboratory testing. The four main tests are a potassium hydroxide smear, culture, histology examination, and polymerase chain reaction. The sample examined is generally nail scrapings or clippings. These being from as far up the nail as possible.Nail plate biopsy with periodic acid-Schiff stain appear more useful than culture or direct KOH examination. To reliably identify nondermatophyte molds, several samples may be necessary. Classification
There are five classic types of onychomycosis:
Distal subungual onychomycosis is the most common form of tinea unguium and is usually caused by Trichophyton rubrum, which invades the nail bed and the underside of the nail plate. White superficial onychomycosis (WSO) is caused by fungal invasion of the superficial layers of the nail plate to form "white islands" on the plate. It accounts for around 10 percent of onychomycosis cases. In some cases, WSO is a misdiagnosis of "keratins granulations" which are not a fungus, but a reaction to nail polish that can cause the nails to have a chalky white appearance.
A syphilid is any of the cutaneous and mucous membrane lesions characteristic of secondary and tertiary syphilis.It appears about 10 weeks after infection. Patient may present with prodromal symptoms such as fever, acratia, myalgia arthralgia, headache, anorexia. Its eruption pattern is macular, papular,  follicular papules, or pustule, symmetrical, generalized and dense, round or oval in shape, and is red copper in color. See also
Id reactions
List of cutaneous conditions


== References ==