Athlete’s foot, medically known as tinea pedis, is a common fungal infection affecting the skin on the feet. It frequently causes symptoms such as itching, scaling, cracking, and redness, often appearing between the toes, on the soles, or sides of the feet. While visible signs can suggest athlete’s foot, a microscopic examination provides a more definitive diagnosis, especially when symptoms are not typical or other skin conditions are involved.
The Fungal Culprit
Athlete’s foot is caused by a group of fungi known as dermatophytes. These fungi feed on keratin, a protein found in the outer layers of human skin, hair, and nails, allowing them to colonize these body parts.
The most common types of dermatophytes responsible for athlete’s foot belong to the genera Trichophyton, Epidermophyton, and Microsporum. These organisms require warm, moist environments to multiply, which is why feet, especially when enclosed in shoes and socks, provide an ideal breeding ground.
Preparing for the Microscopic View
To view fungal elements under a microscope, a sample of the affected skin is collected. This involves gently scraping skin flakes from the active edges of the rash or between the toes using a blunt scalpel or glass slide. Collecting material from the most infected area ensures the presence of fungal elements.
Once collected, the skin scrapings are placed onto a microscope slide. A solution of potassium hydroxide (KOH) is then added to the sample. KOH dissolves human skin cells and other cellular debris, leaving alkali-resistant fungal structures intact and more visible. The slide may be gently heated to speed up this clearing process before microscopic examination.
What Appears Under the Lens
When a prepared skin sample is examined under a microscope, the characteristic features of dermatophytes become apparent. The most notable structures are fungal hyphae, which appear as long, branching, thread-like filaments. These hyphae often have internal cross-walls called septa, making them septate hyphae.
These fungal filaments appear clear or refractile, meaning they bend light, making them stand out against the cleared background of dissolved skin cells. They can vary in length and may show irregular branching patterns. Hyphae may also break apart into barrel-shaped or rectangular segments called arthroconidia.
The presence of these distinct hyphae and arthroconidia confirms a fungal infection. Their appearance helps differentiate true fungal elements from artifacts like cotton fibers or epidermal cell edges, which can mimic fungal structures but lack characteristic branching and septation.
The Diagnostic Significance
Microscopic examination of skin scrapings is important for accurately diagnosing athlete’s foot. Identifying fungal hyphae and/or spores under the microscope offers direct evidence of a dermatophyte infection. This quick and cost-effective method provides results within minutes, allowing for prompt clinical decisions.
This diagnostic step is useful for distinguishing athlete’s foot from other skin conditions with similar symptoms, such as eczema, psoriasis, or bacterial infections. While clinical appearance can suggest athlete’s foot, microscopic confirmation helps avoid misdiagnosis and ensures effective antifungal treatment.