Tinea nigra
Other names: Superficial phaeohyphomycosis, tinea nigra plantaris[1]
Tinea nigra of the palm
Specialty	Dermatology
Symptoms	One or more dark brown, painless spots on palms or soles[2]
Causes	Hortaea wernecki[2]
Diagnostic method	Visualisation,dermoscopy,microscopy, culture[1]
Differential diagnosis	Addison's disease,syphilis,pinta,yaws,melanoma,lentigines,palmer lichen planus,junctional melanocytes nevus[1]
Treatment	Antifungals, scraping the lesion[2]
Medication	TopicalWhitfield's ointment orsalicylic acid,itraconazole by mouth[1]
Frequency	Uncommon, female > male, children and young adults[1]

Tinea nigra is afungal infection of thetop layer of skin.^[1] It typically presents as a single 1 to 5 cm dark brown or black, non-scaly, flat, painless patch on the palms of the hand or soles of the foot.^[1] There is little or no skin inflammation.^[1] Typically it occurs in people who are otherwise healthy.^[1]

It is a type ofphaeohyphomycosis rather than atinea.^[1] Most cases are caused byHortaea wernecki, a pigmented fungus, which is a dark yeast found in sewage, soil, rotting plant matter, and places with a high salt content such as moldy salted fish or on beaches, where contact with sand may result in transmission.^[1][2] Infection is by direct contact.^[1] The fungus enters and remains in the outer dead layer of skin, with no invasion of deeper tissues.^[1]

Diagnosis is looking at the rash,dermoscopy,microscopy or culture of skin scrapings.^[1] Other conditions that may present similarly includesAddison's disease,syphilis,pinta,yaws,melanoma,lentigines,palmer lichen planus. andjunctional melanocytes nevus.^[1] Treatment is with topicalWhitfield's ointment orsalicylic acid ointment.^[1] Topicalantifungals oritraconazole by mouth are other options.^[3] Scraping the lesion can be curative.^[2] Prevention is by generalhygiene measures.^[1]

Tinea nigra is uncommon.^[1] It generally occurs intropical andsubtropical countries of Central or South America, theCaribbean, Europe, South East Asia, Australia, and the Far East.^[1] It is rare in Japan though not uncommon in the US.^[1] The disease was first described byAlexandre Cerqueira from Brazil in 1891.^[1] No cases in animals have been reported.^[1]

Signs and symptoms

It typically presents as a single 1 to 5cm dark brown-black, non-scaly, flat, painless patch on the palms of the hands and the soles of the feet of healthy people.^[1] There may be multiple spots.^[1]

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  Brown colored macule of tinea nigra

Causes

Tinea nigra is caused by the fungus formerly classified asCladosporium werneckii, but more recently classified asHortaea werneckii.^[4] The causative organism has also been described asPhaeoannellomyces werneckii.^[5] Tinea nigra is extremely superficial and can be removed from the skin by forceful scraping. It tends to appear in areas whereeccrine sweat glands are highly concentrated. Infections generally start to appear on the skin around 2–7 weeks post inoculation.

The ability ofH. werneckii to tolerate high salt concentrations and acidic conditions allows it to flourish inside thestratum corneum.H. wernickii tends remain localized in one spot or region, and produces darkly-colored, brown macules on the skin due to the production of a melanin-like substance.^[6]

Diagnosis

Diagnosis of tinea nigra is made based on microscopic examination of stratum corneum skin scrapings obtained by using a scalpel. The scrapings are mixed withpotassium hydroxide (KOH).^[7] The KOHlyses the nonfungal debris.^[7] The skin scrapings are cultured onSabouraud's agar at 25°C and allowed to grow for about a week.H. werneckii can generally be distinguished due to its two-celled yeast form and the presence of septate hyphae with thick, darkly pigmented walls.^[6]

Treatment

Treatment consists of topical application of dandruff shampoo, which contains selenium sulfide, over the skin. Topical antifungal imidazoles such as ketoconazole, itraconazole, and miconazole may also be used. Imidazoles are generally used twice daily for a two-week period. This is the same treatment plan for tinea orpityriasis versicolor. Other treatment methods include the use of epidermal tape stripping, Undecylenic acid, and other topical agents such asciclopirox. Once a tinea nigra infection has been eradicated from the host, it is not likely to reoccur.^[6]

Epidemiology

Tinea nigra is commonly found in Africa, Asia, Central America, and South America. It is typically not found in the United States or Europe, although cases have been documented in theSoutheastern United States. People of all ages can be infected; however, it is generally more apparent in children and younger adults. Females are three times more likely than males to become infected.^[6]

See also

• List of cutaneous conditions

References

External links

• DermAtlas1049165786
• DermNetfungal/tinea-nigra

• Pages with script errors
• Animal fungal diseases
• Mycosis-related cutaneous conditions
• RTT