Historical treatments have used alcoholic tinctures of heavy metals, such as mercury bichloride. The application of antifungal shampoos such as pyrithione zinc, formaldehyde and salicylic acid is effective against black piedra. Oral therapy with itraconazole or terbinafine also causes nodules to break down over time. Removal of affected hair and treatment with topical agents is also effective and results in very low recurrences rates. However, even in the absence of treatment, spontaneous remission may occur.Terbinafine has been used in the treatment. Cosmetic uses
Black piedra is sometimes cultivated for cosmetic purposes due to social factors that favour a specific hair colour, which makes them more attractive in their society. Several Indian tribes located from Panama have been known to use several methods in order to darken the hair of albino individuals within their community. One of these methods is the cultivation of black piedra for an extensive period of time in the individuals hair. In Malaysia the nodules of black piedra are very attractive and women are encouraged to sleep with their hair buried in the soil to encourage growth of the black nodules. Similar taxa
The genus Piedraia contains another species known as Piedraia quintanilhae, which is more common in chimpanzees than humans. It differs from P. hortae in terms of the ascospores do not have any attachments. Another species known as Trichosporon biegelii is commonly known to cause white piedra . White piedra is more common in temperate and semitropical climates, such as South America, Asia, Europe, Japan, and parts of the southern United States.
Keratoacanthoma (KA) is a common low-grade (unlikely to metastasize or invade) rapidly-growing skin tumour that is believed to originate from the hair follicle (pilosebaceous unit) and can resemble squamous cell carcinoma.The defining characteristic of a keratoacanthoma is that it is dome-shaped, symmetrical, surrounded by a smooth wall of inflamed skin, and capped with keratin scales and debris. It grows rapidly, reaching a large size within days or weeks, and if untreated for months will almost always starve itself of nourishment, necrose (die), slough, and heal with scarring. Keratoacanthoma is commonly found on sun-exposed skin, often face, forearms and hands. It is rarely found at a mucocutaneous junction or on mucous membranes.Keratoacanthoma may be difficult to distinguish visually from a skin cancer. Under the microscope, keratoacanthoma very closely resembles squamous cell carcinoma. In order to differentiate between the two, almost the entire structure needs to be removed and examined. While some pathologists classify keratoacanthoma as a distinct entity and not a malignancy, about 6% of clinical and histological keratoacanthomas do progress to invasive and aggressive squamous cell cancers; some pathologists may label KA as "well-differentiated squamous cell carcinoma, keratoacanthoma variant", and prompt definitive surgery may be recommended. Classification
Frequently reported and reclassified over the last century, keratoacanthoma can be divided into various subtypes and despite being considered benign, their unpredictable behaviour has warranted the same attention as with squamous cell carcinoma.Keratoacanthomas may be divided into the following types:: 763–764 : 643–646 
Giant keratoacanthomas are a variant of keratoacanthoma, which may reach dimensions of several centimeters.