White Piedra is a superficial fungal infection of the hair shaft caused by yeast-like fungi belonging to the Trichosporon genus. It is a condition that affects the hair fiber itself, not the scalp or the skin underneath. While generally asymptomatic, this infection is characterized by the formation of small, irregular growths along the length of the hair.
The Defining Physical Characteristics
The most prominent feature of White Piedra is the presence of nodules, often referred to as “piedras,” which are masses of fungal material adhering to the hair. These nodules are typically white, beige, or light tan in color, giving the infection its name. They are not hard or stone-like, but possess a distinctively soft, gelatinous, or gritty texture when touched.
The fungal material forms an irregular cuff that completely encircles the hair shaft, resembling a soft sleeve around the fiber. Multiple nodules can appear along a single hair strand, sometimes coalescing into larger, more noticeable masses. These individual growths are usually quite small, often measuring 1 millimeter or less in diameter.
A significant characteristic of these fungal growths is their attachment to the hair fiber. Unlike other hair-related conditions, the nodules of White Piedra are relatively loosely attached, meaning they can often be slid off or detached from the hair shaft with minimal effort. The infection remains entirely on the outer surface of the hair, not invading the hair’s internal cuticle.
Common Locations on the Body
The location of the infection is a strong identifying factor for White Piedra, as the fungus shows a clear preference for certain types of hair. It most commonly affects body hair, particularly in regions that are naturally more humid and warm. The axillary (armpit) and pubic hair are the most frequent sites where the fungal nodules develop.
Beyond these areas, White Piedra can also be found in facial hair, including the beard and mustache. While less common, the infection may also appear on the finer hairs of the eyebrows and eyelashes. This preference for non-scalp hair is often linked to the higher moisture and sebum levels present in these specific body regions.
Telling White Piedra Apart From Other Conditions
The appearance of small white or light-colored nodules on the hair can easily be confused with other common conditions, making differentiation important.
Lice Nits
One frequent confusion is with lice nits, which are the eggs of head lice. Nits are firmly glued or cemented to the hair shaft and are extremely difficult to remove by sliding or pulling. In contrast, the soft nodules of White Piedra are easily removable and do not require the scraping force needed to dislodge a nit.
Black Piedra
White Piedra is also distinct from Black Piedra, which is caused by a different fungus, Piedraia hortae. Black Piedra presents as dark brown or black nodules that are characteristically hard and firmly cemented to the hair shaft. Furthermore, Black Piedra typically affects the scalp, while White Piedra is predominantly found on body hair.
Hair Casts
Another common differential is the presence of non-infectious hair casts or sleeves. These are often debris from hair product buildup or shed root sheath material. Hair casts are typically mobile and slide freely up and down the hair shaft without adhering to it. The Trichosporon nodules, however, are true fungal masses that encase the hair and, while soft, are more adherent than simple cosmetic debris.