Tinea nigra

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File:Hortaea-werneckii-fungus--causes-tinea-nigra.jpg
Micrograph of the fungus Hortaea werneckii, the causative agent of tinea nigra
Tinea nigra
ICD-10 B36.1
DiseasesDB 32450
eMedicine derm/890 

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Kiran Singh, M.D. [2]

Overview

Tinea nigra (also known as "superficial phaeohyphomycosis,"[1] and "Tinea nigra palmaris et plantaris"[1]) is a superficial fungal infection that causes dark brown to black painless patches on the palms of the hands and the soles of the feet.[2]:311

Causes

This infection is caused by the fungus formerly classified as Exophiala werneckii but more recently classified as Hortaea werneckii.[3]

The causative organism has also been described as Phaeoannellomyces werneckii.[4]

Diagnosis

Diagnosis of tinea nigra causing fungus is made on microscopic examination of skin scrapings, mixed with potassium hydroxide (KOH).[5] The KOH lyses the nonfungal debris.[5]

Physical Examination

Skin

Extremities

Differential diagnosis

Tinea nigra must be differentiated from other diseases presenting with an erythmatous, scaly, annular and pruritic rash. The differentials include the following:

Name of superficial infection Clinical presentation Extension to hair follicle Fungus(i) Systemic disease KOH preparations Morphology in tissue sections
Tinea or ringworm Round lesions with scaly border, accompanied by pruritis and burning Yes; when suppurative known as kerion, when chronic known as Majocchi's granuloma Dermatophytes (Epidermophyton spp., Trichophyton spp., Microsporum spp.) Very rare but can invade the dermis and soft tissues, causing mycetomas Hyphae with or without septations Hyphae cannot be visualized in the keratin with H&E, special stains are needed
Tinea versicolor Hypo and hyperpigmentation in patients with oily and sweaty skin, fine scales when scratching Yes, known as Pityrosporum folliculits Malassezia spp. Systemic infections may occur in premature neonates receiving parenteral nutrition and in other immunosuppressed hosts Yeasts and hyphae (“spaghetti and meat balls”) Faintly basophilic hyphae in the stratum corneum
Tinea nigra Brown to black macule, usually on palms, with some scaling No Phaeoannellomyces werneckii Not described Darkly pigmented, septated, and branching hyphae Pigmented hyphae in the stratum corneum
White piedra Creamy-white, small, soft nodules in hair shafts No Trichosporon spp. Immunosuppressed patients may have lung infiltrates, renal involvement, and fungemia Septate hyphae perpendicular to hair shaft Not used for diagnosis
Black piedra Hard dark nodules in hair shafts No Piedraia hortae Not described Collections of crescent ascospores surrounded by pigmented hyphae Not used for diagnosis
Superficial candidiasis Intertrigo, chronic paronychia, onychodystrophy, cheilitis Yes Candida spp. Yes, particularly in patients with AIDS and depending on the level of immunosuppression Yeasts, pseudohyphae may be observed Fungal elements may be seen through the biopsy, vascular invasion must be determined

Treatment

Treatment consists of topical application of dandruff shampoo, which contains selenium sulfide, over the skin. Topical antifungal imidazoles may also be used, such as Ketoconazole. This is the same treatment plan for tinea or pityriasis versicolor.

See also

References

  1. 1.0 1.1 Rapini, Ronald P.; Bolognia, Jean L.; Jorizzo, Joseph L. (2007). Dermatology: 2-Volume Set. St. Louis: Mosby. pp. Chapter 76. ISBN 1-4160-2999-0. 
  2. James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0. 
  3. Murray, Patrick R.; Rosenthal, Ken S.; Pfaller, Michael A. (2005). Medical Microbiology (5th ed.). Elsevier Mosby. 
  4. Pegas JR, Criado PR, Lucena SK, de Oliveira MA (2003). "Tinea nigra: report of two cases in infants". Pediatric dermatology. 20 (4): 315–7. PMID 12869152. doi:10.1046/j.1525-1470.2003.20408.x. 
  5. 5.0 5.1 Gladwin, Mark; Trattler, Bill. Clinical Microbiology (4th ed.). p. 196. 
  6. 6.00 6.01 6.02 6.03 6.04 6.05 6.06 6.07 6.08 6.09 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18 6.19 6.20 6.21 6.22 6.23 6.24 6.25 6.26 6.27 6.28 6.29 6.30 6.31 6.32 6.33 6.34 6.35 6.36 6.37 6.38 6.39 6.40 6.41 6.42 6.43 6.44 6.45 6.46 6.47 6.48 6.49 6.50 6.51 6.52 6.53 6.54 6.55 6.56 6.57 6.58 6.59 6.60 6.61 "Dermatology Atlas". 

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