Dermatology - Tinea Unguium

Dermatology - Tinea Unguium 
Tinea unguium is a fungal infection of the nails that typically does not go away on its own.
The onset often occurs throughout maturity, and the frequency of occurrence seems to rise with age. Transmission occurs by direct contact or contact with contaminated objects, known as fomites. This mode of transmission is most typically observed among family members.

The nails lose their protective and manipulative functions, which can result in pain in the toenail when pressure is applied by shoes. This can also lead to secondary bacterial infections and ulcerations of the underlying nail bed. Complications are more prevalent among individuals with impaired immune systems and those with diabetes. Toenails are more frequently affected than fingernails. Fingernail involvement typically occurs on one side. The typical pattern including fingernails consists of two feet and one hand.
​
An area of discoloration, typically with clear boundaries, appears on the lower surface of the nail and nail bed. Initially white, it gradually changes to a brown or black color. The nail can get progressively affected over a few weeks or gradually over several months or even years. The nail undergoes increasing infection, resulting in opacity, thickening, cracking, fragility, and elevation due to the accumulation of hyperkeratotic material in the hyponychium. The white streaks, clearly defined and starting at the outer edge of the nail and spreading towards the base, are packed with a combination of keratin debris and air.

The diagnosis is established by confirming the clinical signs through direct microscopic examination of nail clippings using potassium hydroxide preparation, and/or by isolating the pathogenic fungus through culture.
The differential diagnosis comprises psoriatic nails (characterized by "oil drop" staining of the distal nail bed and nail pits, which is observed in psoriasis but not onychomycosis), paronychial psoriasis or eczema, Reiter syndrome and keratoderma blennorrhagicum, onychogryphosis, pincer nails, congenital nail dystrophies, and nail trauma.


Advise the patient to remove damaged nails and administer oral antifungal medication (terbinafine 250 mg per day for 6-16 weeks). The medication can be discontinued once the KOH preparation or culture test shows no signs of infection, even if the nail lesions have not completely healed yet due to the sluggish nail development.