Subclinical Onychomycosis in Apparently Healthy Adults

Onychomycosis is a frequent chronic nail infection, with a worldwide prevalence of 5.5% making it the most common nail disease, and its incidence increases with age. Clinically, it causes discoloration and thickening of the nail plate and may be accompanied by onycholysis. However, little is known of the subclinical infection.

We studied adult male and female outpatients auto-referred as healthy and that had healthy appearing toenails. Nail distal clippings were obtained from the right first toenail. This sample was stained with PAS and observed by an expert dermatopathologist searching for fungal structures.

A total of 32 samples were included: 8 from men (25%) and 24 from women (75%), with ages ranging from 27 to 66 years (mean age of 43 years). Twenty-four patients did not present any histopathological finding suggestive of infection (75%), while 7 patients had a single finding (spores or hyphae) (21.8%), and 1 patient had both findings (3.12%).

We found 4 patients with yeasts, 3 with hyphae, and 1 patient with a combined infection with both yeasts and hyphae (3.1%). These add up to 25% of the clinically apparent healthy nails. Our results show that we still have much to learn from the initial stages of onychomycosis and that our population probably has higher incidence of this nail disease, so we must be alert to subtle nail changes. As our participants signed an informed consent, we will contact those that resulted positive for follow up consultations.