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Background
Tinea nigra is a superficial fungal infection caused by a class of fungus called dematiaceous fungi. The causative organism is Exophiala werneckii (Phaeoanellomyces werneckii). As the name suggests, patients present with an asymptomatic, well demarcated, slow growing pigmented macule on the palms or soles.
OUTLINE
PATHOGENESIS CHARACTERIZATION Exophiala werneckii (Phaeoanellomyces werneckii)
LABORATORY/
RADIOLOGIC/
OTHER TESTSCHARACTERIZATION Laboratory Markers May be cultured on Sabouraud or Dermatophyte test media PCR
- Specific oligonucleotide primers for identification of Hortaea werneckii, a causative agent of tinea nigra.
Abliz P, Fukushima K, Takizawa K, Miyaji M, Nishimura K.
Research Center for Pathogenic Fungi and Microbial Toxicoses, Chiba University, Chiba, Japan.
Diagn Microbiol Infect Dis. 2003 Jun;46(2):89-93. Abstract quote
Hortaea werneckii, a black yeast-like hyphomycete that is widely distributed in tropical and subtropical environments, can cause superficial mycotic infection in humans. This fungus was recently isolated from superficial infectious lesions of a guinea pig in Japan.
An oligonucleotide primer set specific for Hortaea werneckii was designed on the basis of the internal transcribed spacer regions of the ribosomal DNA (rDNA). Polymerase chain reaction (PCR) with this primer set yielded a 306 bp PCR amplicon from only H. werneckii.
This primer set did not amplify DNAs of 42 other related dematiaceous species, including the medically important dematiaceous fungi Cladophialophora carrionii, Fonsecaea pedrosoi, Phialophora verrucosa, and Exophiala dermatitidis, and eight species of medically important yeasts, including Candida (C.) albicans, C. dublinensis, C. glabrata, C. parapsilosis, C. tropicalis, Cryptococcus neoformans var. neoformans, Malassezia furfur, and Trichosporon asahii var. asahii. PCR with this primer set may be a useful technique for rapid identification of H. werneckii.
CLINICAL VARIANTS CHARACTERIZATION BILATERAL
- Bilateral tinea nigra plantaris and tinea nigra plantaris mimicking melanoma.
Tseng SS, Whittier S, Miller SR, Zalar GL.
Department of Dermatology, New York-Presbyterian Hospital, Columbia Presbyterian Center, New York, USA.
Cutis. 1999 Oct;64(4):265-8. Abstract quote
Tinea nigra, a superficial fungal infection caused by Phaeoannellomyces werneckii, presents as a hyperpigmented, nonscaling macule of variable size and shape.
Typically lacking induration, erythema, or pruritus, these "ink spot" lesions may resemble junctional nevi or malignant melanoma.
Rapid, noninvasive diagnosis can be provided by potassium hydroxide examination, demonstrating numerous large, dematiaceous hyphae.PEDIATRIC
- Tinea nigra: report of two cases in infants.
Pegas JR, Criado PR, Lucena SK, de Oliveira MA.
Complexo Hospitalar Padre Bento de Guarulhos, Sao Paulo, Brazil.
Pediatr Dermatol. 2003 Jul-Aug;20(4):315-7. Abstract quote
Tinea nigra, a relatively uncommon mycosis caused by Phaeoannelomyces werneckii, is typically seen as an asymptomatic brown or black macule on the hands and feet.
We present two cases of tinea nigra in children in Sao Paulo, Brazil, and alert readers to the potential for confusion with melanocytic lesions.
HISTOLOGICAL TYPES CHARACTERIZATION SKIN Pigmented hyphae with KOH scraping
Stratum corneum shows numerous spaces containing the hyphae or spores
VARIANTS
DIFFERENTIAL DIAGNOSIS CHARACTERIZATION MELANOMA
- Tinea nigra palmaris: differentiation from malignant melanoma or junctional nevi.
Hall J, Perry VE.
Baylor College of Medicine, Houston, Texas, USA.
Cutis. 1998 Jul;62(1):45-6. Abstract quote
Tinea nigra usually presents as a brown to black macule on the palmar or plantar skin and is sometimes misdiagnosed as a malignant melanoma or as a junctional nevus, prompting unnecessary surgical procedures and anguish for the patient.
Superficial scraping of the skin for microscopic inspection with potassium hydroxide reveals pigmented hyphae, easily confirming the diagnosis of tinea nigra.
PROGNOSIS AND TREATMENT CHARACTERIZATION TREATMENT
- Therapy of tinea nigra plantaris.
Sayegh-Carreno R, Abramovits-Ackerman W, Giron GP.
Department of Dermatology, Central University of Venezuela, Caracas.
Int J Dermatol. 1989 Jan-Feb;28(1):46-8. Abstract quote
Four cases of tinea nigra plantaris are presented. The therapeutic approaches used by different dermatologists who treated these patients are analyzed in order to obtain a meaningful conclusion on how to best manage this infrequent entity.
We conclude that the visible affected skin should be scraped off before using either ciclopiroxolamine or an imidazole topically; systemic therapy is not recommended.Cutis 1998;62:45-46.
Henry JB. Clinical Diagnosis and Management by Laboratory Methods. Twentieth Edition. WB Saunders. 2001.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 5th Edition. McGraw-Hill. 1999.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fourth Edition. Mosby 2001.
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Last Updated June 15, 2005
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