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Revista chilena de pediatría

Print version ISSN 0370-4106

Rev. chil. pediatr. vol.89 no.4 Santiago Aug. 2018

http://dx.doi.org/10.4067/S0370-41062018005000404 

CLINICAL CASE

Tinea nigra: Report of three pediatrics cases

María Consuelo Giordano L.A 

Alicia De la Fuente L.A 

María Bernardita Lorca J.B 

Daniela Kramer H.B  C 

A Medical School Intern, Universidad del Desarrollo-Clínica Alemana, Chile.

B Dermatologist Clínica Alemana de Santiago, Chile.

C Pediatric dermatologist, Hospital Luis Calvo Mackenna, Chile.

Abstract:

Introduction:

Tinea nigra is a superficial mycosis caused by Hortaea werneckii. Its clinical characte ristic is the appearance of a blackish brown macula of rapid growth, caused by the pigment produced by the fungus itself. The presence of a dark, fast growing, acral pigmentary lesion causes concern among patients and their treating physician about the possibility of a malignant pigmentary lesion.

Objective:

To present a series of three clinical cases in pediatric patients with this pathology and to show the tools that help to make a differential diagnosis.

Clinical cases:

Three patients between three and five years of age, which present a macular pigmented lesion on palms or soles, whose parents reported a rapid growth over a short period of time. Two of the patients reported previous trips to the Caribbean. Clinical and dermatoscopy suspicion of tinea nigra lead to a direct mycological exa mination, which confirmed the diagnosis. In all three cases, treatment with topical antifungals led to complete healing of the lesions.

Conclusions:

Although tinea nigra is rare in a dry climate, increasing travel of patients to tropical countries will increase the number of cases. Dermatoscopy and direct mycological examination are the tools that allow performing a correct diagnosis and avoiding unne cessary biopsies and/or surgeries.

Keywords: Tinea nigra; Hortaea werneckii; Dermatoscopy

Introduction

Tinea nigra is a superficial cutaneous mycoses caused by Hortaea werneckii (H. werneckii), described by McGinnis and Schell in 1985, previously named Phaeoannellomyces werneckii and Exophiala werneckii. The current taxonomic classification of this fungus co rresponds to the Kingdom Fungi: Phylum Ascomycota; Class: Dothideomycetes; Order: Dothidales and Genus: Hortae1.

Tinea nigra is a mycosis of universal distribution, mainly in tropical and subtropical climates, with a higher incidence rate in Central and South America (Panama, Costa Rica, Mexico, Colombia, Venezuela, Brazil, Argentina, Uruguay and Peru), Asia (India, Sri Lanka and Myanmar), Shores of Africa and the Caribbean2. In the literature, there are 155 reported cases of tinea nigra in Latin America between 1966 and 2017.

Due to the low incidence in Chile, the objective of this report is to present 3 characteristic cases in children, and to analyze diagnostic and therapeutic tools.

Clinical cases

Case 1

A 5-year-old male patient with history of a pig mented macula on the foot sole, asymptomatic and with a quick growth. In a previous dermatological examination, a plantar nevus was diagnosed, howe ver, the parents requested another opinion due to the quick growth of the lesion. During the interview, the parents did not refer any recent trips or animal bites. On physical examination, it was possible to observe a brown two-centimeter macula, with irregular pigmentation and shape; it had defined edges, without scales or signs of inflammation (Figure 1). On dermatoscopy, a non-melanocytic lesion was observed, which was characterized by multiple cross-linked brown strands forming a heterogeneous pigment network (Figure 2). In the mycological study, various pigmented septate filaments, which are characteristic of H. werneckii (Fi gure 3) were seen. The fungal etiology of the pigmen ted macula reduced the family anxiety after ruling out a nevoid lesion. Topical antimycotics (ciclopirox 1% cream, twice a day for three weeks) were indicated and the patient had a total regression of the lesion.

Figure 1 Pigmented macule on the foot sole. 

Figure 2 Dermatoscopy reveals a non melanocytic lesión (multiple interlacing brown strands). 

Figure 3 Pigmented septated hyphae characteristic of H. Werneckii. 

Case 2

A 3-year-old male patient with a six-month his tory of a pigmented lesion on the foot sole, which had grown, and without associated symptoms. The patient had visited the Caribbean before the onset of the clinical manifestations. He was referred by his pediatri cian due to a “mole which has grown” (Figure 4). The dermatoscopy ruled out a nevoid lesion and multiple septated filaments were observed on the KOH. The treatment indicated was 15% urea and 1% bifonazole cream for three weeks and the patient had an excellent evolution.

Figure 4 Light brown macule on the foot sole. 

Case 3

A 3-year-old male patient, with a four-month his tory of a pigmented, quick growing lesion on the palm. The patient was referred by his pediatrician due to a “recent mole”, which was asymptomatic (Figure 5). He had visited the Caribbean in the last semester. The dermatoscopic diagnosis and the mycological confirma tion validated the diagnosis of tinea nigra. The patient had an excellent response to 1% ciclopirox cream twice daily for three weeks.

Figure 5 Fast growing macular pigmented lesión on the hand palm. 

Discussion

In the differential diagnosis, it is very important to perform a correct anamnesis, emphasizing in the progression time, associated symptoms, trips abroad, presence of associated hyperhidrosis, history of bi tes, drug intake, and occupational or recreational exposure to chemical substances. The dermatoscopy can often be an essential tool in order to differentia te between pigmentation of melanocytic origin, both benign and malignant, from other non-melanocytic pigmentations.

The mycological study, both direct KOH exami nation and culture, is the key element to confirm the etiological diagnosis in the cases of tinea nigra. The fi lament pigmentation allows differentiating tinea nigra from other types of dermatophytosis1.

This disease is more frequent in females than males (2:1) and has a higher incidence rate in children and young adults3.

Pathogenesis

H. werneckii is a halophilic species, which has the ability to survive in high salt concentrations so that most of the cases are reported in coastal zones1. It is an environmental pathogen found in plants, decom posing plant material, sand, wastewaters, sea mollusks, earth, food with high salt content, even in showers in humid environments. In humans, it feeds the lipid ma terial on the surface of the skin. It tolerates high salt concentrations and low pH levels; therefore, it grows adequately in the stratum corneum when the humidity and heat conditions are adequate4. The predisposing factors for the inoculation of the fungus in the stratum corneum are hyperhidrosis, presence of micro-trau mas, such as running barefoot, playing water sports or playing on the river or lake banks3 and animal bites5.

It is unknown if it is possible to directly transmit this microorganism from person to person4.

After an incubation period of 15 to 20 days, the H. werneckii grows forming filaments and brown spores, remaining exclusively at the stratum corneum level. Changes in skin color are due to the accumulation of a substance similar to the melanin inside the fungus6.

Clinical presentation

It often appears as an asymptomatic and well de limited, brown, green or grey, single macula or patch, which can be velvety or with a slight scaling. It has also been clinically described as having the aspect of “salt and pepper”7. The most common localization is on the palm of the hand, usually unilateral, and on the feet sole (10% to 20%)8, it can also appear on the neck and trunk. Bilateral involvement is uncommon9. It must be taken into account as part of the differential diagnosis of pigmented lesions such as melanocytic nevi, especially those junctional and acral, lentigo maligna, and malignant melanoma. It should also be considered as a diagnostic alternative in inflammatory pathology, such as fixed drug eruption, post-inflam matory hyperpigmentation or in cases of staining due to chemical products, pigments and dyes (henna, sil ver nitrate)10.

Dermatoscopy

The dermatoscopy, a non-invasive and handy method that allows the visualization of amplified cuta neous structures, is useful in both pigmented and non pigmented lesions. The dermatoscope is a modified glass that reveals the cutaneous surface and magnifies the image ten times, which allows the visualization of submacroscopic structures. The presence of polarized light in some of these devices allows its use without direct contact with the skin, which prevents the trans mission of infectious agents. Its utility in the diagnosis of skin infections and infestations is demonstrated and it is known as Entodermoscopy11.

It is a quick and effective tool for clinical orienta tion for the diagnostic suspicion of tinea nigra. In this pathology, the presence of multiple light brown thin lines that cross forming a weave is characteristic12. It has also been described as a hyperchromic patch with a regular distribution of the pigmentation and the pre sence of spicules on the edges13. In the case of benign acral nevi, the presence of nevus cell nests, which tend to localize predominantly in the furrows is characteris tic14. The pigmentation does not follow the parallel rid ges pattern described for melanomas, even when there are two reports that reject this15,16.

Diagnosis

In most of the patients, the diagnosis is clinical and dermatoscopical, which can be confirmed by a direct mycological KOH test or fungal culture. The visuali zation of the scale smear is often diagnostic, where it is possible to observe pigmented septate filaments4. H. werneckii cultures grow fast in usual fungal media, observing black colonies in five to eight days, creamy at first, then fluffy17.

Treatment

Topical keratolytics are effective, such as Whitfield’s ointment (salicylic acid 3% and benzoic acid 6%), and urea-based products, as are topical antifungals (azoles and allylamines). The use of topical terbinafine and butenafine have recently also reported with an effective response. With these measures, it is possible to accom plish a complete recovery in two to four weeks; howe ver, there can be a recurrence in case of re-exposure. In the literature, there are also reports of successful cases where the patients were treated with oral itraconazo le, with doses that vary from 100 to 200 mg/day per three to four weeks1,18. Likewise, there are some cases of spontaneous recovery from this mycosis19.

Conclusion

Despite being a rare pathology in dry weather cou ntries such as Chile, its incidence rate can increase due to the globalization and the trend of the popula tion traveling abroad, therefore pigmented lesions of diffwerent etiologies should be considered during exa minations.

Pigmented acral lesions are often a diagnostic cha llenge for the treating physician. The dermatoscopy allows an easy diagnostic approximation by ruling out, in these cases, the presence of nevus-like structures in these lesions.

The examination with mycological test, which con firms the tinea nigra diagnosis, prevents the performance of unnecessary biopsies.

Ethical Responsibilities

Human Beings and animals protection: Disclosure the authors state that the procedures were followed according to the Declaration of Helsinki and the World Medical Association regarding human experimenta tion developed for the medical community.

Data confidentiality: The authors state that they have followed the protocols of their Center and Local regulations on the publication of patient data.

Rights to privacy and informed consent: The authors have obtained the informed consent of the patients and/or subjects referred to in the article. This do cument is in the possession of the correspondence author.

Financial Disclosure: Authors state that no economic support has been asso ciated with the present study.

Conflicts of Interest: Authors declare no conflict of interest regarding the present study.

Referencias:

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Received: December 15, 2017; Accepted: April 23, 2018

Correspondence: María Bernardita Lorca blorca@alemana.cl.

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