On-line version ISSN 1806-4841
An. Bras. Dermatol. vol.79 no.3 Rio de Janeiro May/June 2004
CLINICAL, LABORATORY AND THERAPEUTIC INVESTIGATION
Study of nine observed cases of Tinea Nigra in Greater Vitória (Espírito Santo state, Brazil) over a period of five years*
Lucia Martins Diniz
Assistant Professor, Post-Graduate Service in Dermatology, Emescam, and head of the Mycology Laboratory
BACKGROUND: Tinea Nigra is a rare,
chronic fungal infection of the stratum corneum of the epidermis. It is caused
by a filamentous fungus (Phaeoannellomyces werneckii) and is characterized
by brownish stains, with clear, nondesquamative and asymptomatic borders, commonly
located on the palms of the hand.
OBJECTIVES: To register the presence of cases of Tinea Nigra in Espírito Santo state and describe its epidemiological characteristics.
MATERIAL AND METHODS: Cases clinically diagnosed as Tinea Nigra were sought among the patients submitted to laboratory examinations in order to define fungus presence at the Dermatology Service laboratory in Vitória, from January 1, 1998 to January 1, 2003.
RESULTS: Nine cases of Tinea Nigra were found, all of them affecting Caucasian persons, with damage located on one of the palms of the hands; seven cases (77.7%) were female, six cases (66.6%) were preschool children. All of the cases had laboratorial confirmation.
CONCLUSIONS: a) Nine cases of Tinea Nigra were found, even in the seaside beach region; b) Caucasians, women and children were most commonly affected; c) the common localization is on the palm of the hands, mainly on the left hand
Key words: epidemiology; exophiala; tinea.
Tinea Nigra or keratophytosis negra consists of a chronic fungal infection of the stratum corneum of the epidermis. It was described in Bahia in 1891 by Alexandre Cerqueira, who named it Keratomycosis nigricans palmaris.1-6 In 1921, Parreiras Horta isolated the lesion fungus and classified it as Cladosporium werneckii. In 1985, McGinnis & Schell proposed a new genus for the fungus, due to conidiogenesis by inhalation, named Phaeoannellomyces werneckii (Phaeo = dark; annellomyces = ring). However, in the same year, Nishimura & Miyaji render it a lasting name, Hortae werneckii.7 Rare cases in Venezuela have been determined by Stenella araguata.3,4
Tinea negra has a predilection for tropical and subtropical regions in Asia, Africa, and Central and South America, but there have been cases in North America.1,8 In Brazil, most of the cases reported are in the states of Pernambuco, Bahia, Rio de Janeiro and São Paulo, although sporadic cases were published on the infection arising in Amazonas, Pará, Minas Gerais, Espírito Santo, Rio Grande do Sul, Ceará and Paraná.3,4,7,8,9,10
The disease affects individuals of both sexes and may involve any age range. However, most cases refer to females aged 20 years and under.1,4,5,6,8
Phaeoannellomyces werneckii is a saprobic fungus living alone in the following environments: soil, plants, beach sand, air, decomposing fish and normal skin (scalp and interdigital spaces). Cases frequently appear in costal regions, indicating the possibility of acquiring a fungal infection on the seaside.1,10 In 1994, Uijithof et al. identified Phaeoannellomyces werneckii in areas rich in saline concentration.11,12
The transmission vector remains unknown. The infection has arisen after traumatism and even without any fistulae. The role of cellular immunity or of the local non-specific immunity leading to an imbalance in the host/fungus relation is questioned.1 Reports on family cases may refer to transmission between humans and exposure to the same source of infection.4
The period of incubation of tinea negra varies from two to seven weeks. It is characterized clinically by the initial emergence of one of more stains varying in color from light-brown to black, which join, evolve centrifugally and grow to between one and five centimeters. There is a minimum of desquamation and well-delimited borders. It is asymptomatic and not accompanied by any inflammatory process. It is commonly localized on the palmar regions and the fingers, but rarely on the plants of the feet, dorsal aspect of the hands, cervical region, back, male genitals and wrist. Cases of bilateral palmar localization are very rare.1,4-8,13
A differential diagnosis is recommended with melanocytic nevus, melanoma, secondary syphilis, exogenous pigmentation (dye, silver nitrate, pigment, Indian ink). When lesions are located outside of the palmar regions, they must be differentiated from fixed pigmented erythema, pityriasis versicolor and post-inflammatory hyperchromia, etc.1,8
The laboratorial diagnosis by direct mycological examination, with 20% potassium hydroxide in an aqueous solution of dimethyl sulfoxide and of scales obtained by scraping the lesion, reveals multiple dematiaceous hyphae (resulting from melanin dihydroxynaphthalene pigment), septated, short, with varying diameter, light brown conidia, elliptical, and uni- and bicellular, i.e. all typical characteristics of Phaeoannellomyces werneckii. The seeding of scales stemming from the lesions in a Sabouraud agar medium determines colony growth to be initially yeast-like that was humid, shiny, smooth and spherical. It has an olive-grey color similar to a "drop of oil", growing to its maximum size between 21 and 25 days, at which time a filamentous stripe on the contour can be observed. The colony's micromorphology shows globular yeast-like cells, with an elongated and sinuous mycelium and innumerable septums.11,14,15
Tinea negra may be treated topically with keratolytic agents, like 2 to 4% salicylic acid, and with antifungals: ketoconazole cream, imidazole derives, ciclopirox olamine twice a day for two to three weeks. There is rarely any recurrence.1-4
MATERIAL AND METHODS
This retrospective study is based on data obtained from the stored cards of patients submitted to examinations for research on fungi at the Dermatology Service laboratory of the Santa Casa de Misericórdia at Vitória, ES, from January 1, 1998 to January 1, 2003. From the cards of patients clinically diagnosed with Tinea Negra, the name, age, sex, race, district, and city of residence, the localization of the lesion and results of the direct mycologic examinations and cultures for fungi were noted.
The direct mycologic examination of the desquamations removed by scraping the patients' lesions was performed by applying a 20% potassium hydroxide drop in aqueous solution of dimethyl sulfoxide over a microscope slide set with a coverslip. This preparation was then observed with an optical microscope. The scales were seeded in a Sabouraud agar medium and observed daily for 30 days, for a macroscopic and microscopic investigation of the colony.
From January 1, 1998 to January 1, 2003, 3,350 patients who came from various districts of Greater Vitória were submitted to fungus research at the laboratory, with an average of 670 patients per year. Among them, nine patients (0.26%) had confirmed clinical and laboratory diagnosis of Tinea Negra.
Regarding sex, seven cases (77.7%) were female, and two (22.3%) were male. As for age range, six cases (66.6%) were between three and seven years of age, and three of them (33.4%) were adults. All were Caucasian and clinically showed a single brown stain, with well-defined borders, discretely desquamative and asymptomatic (Figure 1), localized on one of the palms (in one case on the finger), and seven cases (77.7%) on the left hand, and two (22.3%) on the right hand (Table 1).
The direct mycological tests of the lesion scales in every patient showed hyphae that were filamentous, brownish, septated, short, of variable diameter, with light-brown conidia, elliptical, and uni- or bicellular (Figure 2). The cultures in Sabouraud agar medium of all patients' scales macroscopically showed the growth of a yeast-like colony that was humid, shiny, smooth, and spherical, whose color was an olive-grey similar to a "drop of oil" (Figure 3). The micromorphology of colonies using the blue-cotton lactophenol stain is characterized by septated hyphae, blastoconidia and arthroconidia-typical of the Phaeoannellomyces werneckii fungus (Figure 4).
Patients were treated with topical antifungals: some with isoconazole and others with ketoconazole twice daily for 20 days. The condition progressed toward a cure with no recurrence of lesions.
Tinea negra is a fungal infection of the stratum corneum of the epidermis, which appears sporadically. During the period in which this study took place, nine cases of tinea negra were observed.
Mattêde et al.16 published a study in which they isolated the tinea negra agent in seaside beach areas, specifically in Espírito Santo state. Many inhabitants of the Greater Victória region spend their leisure time at the beaches, where they have contact with sand. As tinea negra is rarely observed in this region, given the number of persons frequenting the beaches, it is most likely not the main factor in the spreading of this disease. There is a hypothesis that local immunity participates in an imbalance of the human/fungus relationship, thereby allowing infection by Phaeoannellomyces werneckii. This fungus exhibits lipophilic adhesion to the human skin and lipolitic activity. Its tolerance survives on the skin due to the fact of receiving nourishment from excreted substances.17
Tinea negra affects individuals of both sexes at any age. Meanwhile, the literature shows a higher frequency in females below age 20 years.11 This confirms our own study's data, as seven patients were female and six children varying in age from three to seven years.
In 1986, Montiel observed children commonly showing tinea negra lesions on the palm of the right hand, and adults, on the palm of the left hand. This suggested to the author that the manifestations were related to hyperhidrosis.11 Gondim-Gonçalves et al.8 observed a higher frequency of lesions on the left palmar region. This is a fact that was also made evident in our study because seven patients showed lesions on the left hand. Still, this remains unfavorable to the hypothesis of infection after trauma, because one would expect the right hand, usually the one to be most used, to have a higher frequency of affection.
All results of the direct mycological examinations and cultures in Sabouraud agar medium confirmed the suspected diagnosis. The importance of these examinations must be emphasized especially regarding the differential diagnosis in cases of brown stains appearing mainly on the palmar and plantar regions. They therefore prevent the occurrence of invasive procedures, like melanocytic nevus and melanoma, on the differentiation. An alternative to the differentiation of these pigmentary lesions would be by using dermoscopy. The latter shows a homogeneous, non melanocytic pigmented pattern, which does not follow the dermatoglyphic patterns, as in cases of tinea negra.18
a) Nine cases of Tinea Nigra were found, even in the seaside beach region;
b) Caucasian females and children were most frequently affected;
c) The preferential localization was on the palmar region, with a predilection for the left hand.
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Lucia Martins Diniz
Rua Carlos Martins - nº 634 - Jardim - Camburi
29090-060 Vitória ES
Telefone: (27) 3337-4236 ou 3325- 0940.
Received in June, 15th of 2003.
Approved by the Consultive Council and accepted for publication in March, 12th of 2004.
* Work done at "Santa Casa de Misericordia School of Medicine, Vitória, Espirito Santo" (Emescam).