Tinea nigra by Hortaea werneckii, a report of 22 cases from Mexico

Tinea Nigra: Clinical and Diagnostic Guidance

Tinea nigra is a rare superficial fungal infection characterized by asymptomatic, unilateral, well-defined brown to black macules predominantly affecting the palms and soles. Diagnosis is often challenging due to its rarity and resemblance to other pigmented lesions. This report presents a clinical case, a diagnostic algorithm, and treatment recommendations, emphasizing the role of thorough examination and questioning. We describe the case of a 64-year-old woman of Amerindian (Maya) heritage from Yucatan, Mexico, who presented with a three-month history of a slowly growing dark spot on her left palm. The lesion was asymptomatic, non-scaling, and non-palpable. Palmar skin scrapings, prepared with KOH, revealed pigmented yeast and hyphae, leading to a diagnosis of tinea nigra. Following treatment with topical ketoconazole, the patient's lesions completely resolved at the one-month follow-up. The cultivation of scales confirmed the presence of Hortaea werneckii. Our findings highlight the importance of considering tinea nigra in the differential diagnosis of pigmented lesions on acral surfaces. We propose a diagnostic algorithm to aid healthcare professionals in recognizing this uncommon condition and recommend treatment protocols that effectively resolve the infection within two weeks. This case underscores the necessity for increased awareness and accurate diagnosis of tinea nigra, particularly in non-endemic regions.

Dermatopathology and the Diagnosis of Fungal Infections

Diagnosis of superficial/cutaneous fungal infections from skin, hair and nail samples is generally achieved using microscopy and culture in a microbiology laboratory, however, any presentation that is unusual or subcutaneous is sampled by taking a biopsy. Using histological techniques a tissue biopsy enables a pathologist to perform a full examination of the skin structure, detect any inflammatory processes or the presence of an infectious agent or foreign body. Histopathological examination can give a presumptive diagnosis while a culture result is pending, and may provide valuable diagnostic information if culture fails. This review demonstrates how histopathology contributes to the diagnosis of fungal infections from the superficial to the life threatening.

Tinea Nigra Palmaris

This case report describes multiple coalescing brownish black macules with irregular borders over the left palm and palmar aspect of the digits, with black pigmentary accentuation over the creases.

Hortaea werneckii isolates exhibit different pathogenic potential in the invertebrate infection model Galleria mellonella

Hortaea werneckii is a black yeast with a remarkable tolerance to salt. Most studies have been dedicated to understanding how H. werneckii adapts to hypersaline environments. H. werneckii has an unconventional cell cycle in which it alternates between fission and budding, which is modulated by cell density. Additionally, H. werneckii can cause superficial mycosis of the palm and sole of humans. Here, we determine the impact of salt concentration on the EXF-2000 strain's cell division pattern and morphology by performing timelapse microscopy at different salt concentrations. At low density and no salt, EXF-2000 primarily grows as pseudohyphae dividing mainly by septation. When grown in the presence of salt at a similar concentration to saltwater or hypersaline environments, we observe it grows first by undergoing fission followed by budding at the poles. Then, we examined a collection of 16 isolates in the presence of 0.6M NaCl, including isolates from marine and hypersaline environments and isolates from patients. These isolates exhibit a wide diversity in colony shape and cellular morphology. The isolates grew as yeast, pseudohyphae, and true hyphae, indicating that isolates can exhibit various cell morphologies under similar environmental conditions. We used the insect larvae Galleria mellonella to determine the pathogenic potential of our isolates. We observe that only a subset of isolates can cause death in our model, and there was no correlation between H. werneckii morphology and capacity to cause disease. Taken together, H. werneckii genomic and phenotypic diversity can serve as a model to better understand how phenotypes and pathogenic potential evolve in environmental fungi.

An indigenous inland genotype of the black yeast Hortaea werneckii inhabiting the great pyramid of Giza, Egypt

Within the context of cultural heritage conservation, the biological study of tangible archeological sites is an important task to extend their existence and strengthen the transmission of their cultural value to future generations. In Egypt, a hyper-arid region, a microcolonial fungus with inky black growth was observed on a stone surface in the royal corridor of the Great Pyramid of Giza (King Khufu’s pyramid). The isolate was studied and characterized by microscopic morphometric measurements, evaluation of enzymatic activities, and genotyping techniques. The isolate was identified as Hortaea werneckii, a pleomorphic black yeast that naturally inhabits hypersaline environments and infects human skin. It has been reported from humid temperate, subtropical, and tropical zones, mainly from marine habitats and adjacent areas, and is associated with marine life. Since it was observed in an unusual habitat, it raises the question of its type and origin, whether environmental or clinical. The Egyptian Hortaea werneckii GPS5 isolate was profiled and characterized by adaptive extremophilic tolerance to arid salt stress, low portability to infect human skin, and the capability of solubilizing calcite; besides it was phylogenetically clustered with previous recorded environmental accessions. A profile that matches the biodeterioration fungal agents known as rock-inhabiting fungi, a potential threat to cultural heritage sites that requires attention and prevention plans.

A Special Tinea Nigra Caused by Curvularia lunata: Case Report and Literature Review

Tinea nigra is a superficial fungal infection usually caused by Hortaea werneckii (H. werneckii). We report a special case of tinea nigra in an immunocompetent child who developed a unilateral, rapidly growing pigmented lesion on her palm. Interestingly, Curvularia lunata (C. lunata) was isolated from the lesion scrapes and was identified by both morphological features and molecular biology methods. The lesion was completely cleared by topical naftifine hydrochloride and ketoconazole cream. We present-to the best of our knowledge-the first case of tinea nigra where the causative pathogen was identified as C. lunata. We therefore provide a brief literature review of previously reported cases of tinea nigra to broaden the knowledge of the potential causative pathogens. The etiology, demography, clinical features, diagnostic methods, and treatment of the reviewed cases are summarized and analyzed.

Comparative study of cutaneous melanoma and its associated issues between people of African decent and Caucasians

Cutaneous melanoma is uncommon in people of African descent unlike their Caucasian counterparts. This rarity of cutaneous melanoma in people of African descent makes studies in this group difficult. In the few studies that are available, several differences exist in the incidence, disease severity, course of the disease, treatment modalities and survival rates between these two groups. Observed difference in cutaneous melanoma between people of African descent and Caucasians include; a higher incidence and better prognosis in Caucasians, a low awareness of melanoma, no definite risk factors, presentation with advanced disease, poor melanoma specific survival in people of African descent. Other differences are a better UV-induced DNA damage recovery, acral as opposed to truncal melanoma, female preponderance and lack of preventive measures in people of African descent.

Whole Genome Sequencing and Comparative Genome Analysis of the Halotolerant Deep Sea Black Yeast Hortaea werneckii

Hortaea werneckii, an extreme halotolerant black yeast in the order of Capnodiales, was recently isolated from different stations and depths in the Mediterranean Sea, where it was shown to be the dominant fungal species. In order to explore the genome characteristics of these Mediterranean isolates, we carried out a de-novo sequencing of the genome of one strain isolated at a depth of 3400 m (MC873) and a re-sequencing of one strain taken from a depth of 2500 m (MC848), whose genome was previously sequenced but was highly fragmented. A comparative phylogenomic analysis with other published H. werneckii genomes was also carried out to investigate the evolution of the strains from the deep sea in this environment. A high level of genome completeness was obtained for both genomes, for which genome duplication and an extensive level of heterozygosity (~4.6%) were observed, supporting the recent hypothesis that a genome duplication caused by intraspecific hybridization occurred in most H. werneckii strains. Phylogenetic analyses showed environmental and/or geographical specificity, suggesting a possible evolutionary adaptation of marine H. werneckii strains to the deep sea environment. We release high-quality genome assemblies from marine H. werneckii strains, which provides additional data for further genomics analysis, including niche adaptation, fitness and evolution studies.

Tinea nigra palmaris-associated peritonitis, caused by Hortaea werneckii: The first case report in a peritoneal dialysis patient

We report the first case of peritoneal dialysis (PD) patients with peritonitis from Hortaea werneckii, a halotolerant black yeast-like fungus. The pathogen was confirmed by nucleotide sequences of internal transcribed spacer regions of the ribosomal RNA gene. A potential cause of this infection was tinea nigra on the patient's palm. Therefore, gloving might be advised during PD bag exchange in patients or caregivers who have an obvious lesion of the palm.

Interdigital Tinea Nigra

Tinea nigra is an uncommon superficial dermatomycosis precipitated by Hortaea werneckii, a halophilic and halothermic yeast-like fungus capable of producing a melanin-like substance. This pathogen infiltrates the stratum corneum in the setting of microtrauma and produces an asymptomatic brown to black macule or patch that appears similarly to melanocytic nevi or melanoma. We present a case of a 52-year-old woman who presented to clinic several months after developing a painless, nonpruritic dark brown patch in her left foot inside the fourth toe web. The coloration and location of this lesion would typically prompt biopsy; however, Wood's lamp examination and potassium hydroxide (KOH) preparation were pursued first and demonstrated evidence of infection by H. werneckii. The patient was treated with topical clotrimazole cream and miconazole powder for one month, and her lesions cleared completely. Her lesions did not recur at her three-month follow-up appointment.

Insights into fungal diversity of a shallow-water hydrothermal vent field at Kueishan Island, Taiwan by culture-based and metabarcoding analyses

This paper reports the diversity of fungi associated with substrates collected at a shallow hydrothermal vent field at Kueishan Island, Taiwan, using both culture-based and metabarcoding methods. Culture of fungi from yellow sediment (with visible sulfur granules), black sediment (no visible sulfur granules), the vent crab Xenograpsus testudinatus, seawater and, animal egg samples resulted in a total of 94 isolates. Species identification based on the internal transcribed spacer regions of the rDNA revealed that the yellow sediment samples had the highest species richness with 25 species, followed by the black sediment (23) and the crab (13). The Ascomycota was dominant over the Basidiomycota; the dominant orders were Agaricales, Capnodiales, Eurotiales, Hypocreales, Pleosporales, Polyporales and Xylariales. Hortaea werneckii was the only common fungus isolated from the crab, seawater, yellow and black sediment samples. The metabarcoding analysis amplifying a small fragment of the rDNA (from 18S to 5.8S) recovered 7-27 species from the black sediment and 12-27 species from the yellow sediment samples and all species belonged to the Ascomycota and the Basidiomycota. In the yellow sediments, the dominant order was Pleosporales and this order was also dominant in the black sediment together with Sporidiobolales. Based on the results from both methods, 54 and 49 species were found in the black and yellow sediments, respectively. Overall, a higher proportion of Ascomycota (~70%) over Basidiomycota was recovered in the yellow sediment and the two phyla were equally abundant in the black sediment. The top five dominant fungal orders in descending order based on species richness were Pleosporales>Eurotiales>Polyporales>Hypocreales>Capnodiales in the black sediment samples, and Polyporales>Pleosporales>Eurotiales>Capnodiales>Hypocreales in the yellow sediment samples. This study is the first to observe a high diversity of fungi associated with various substrates at a marine shallow water hydrothermal vent ecosystem. While some fungi found in this study were terrestrial species and their airborne spores might have been deposited into the marine sediment, several pathogenic fungi of animals, including Acremonium spp., Aspergillus spp., Fusarium spp., Malassezia spp., Hortaea werneckii, Parengyodontium album, and Westerdykella dispersa, were recovered suggesting that these fungi may be able to cause diseases of marine animals.

Fungal and bacterial diversity of Svalbard subglacial ice

The composition of fungal and bacterial communities in three polythermal glaciers and associated aquatic environments in Kongsfjorden, Svalbard was analysed using a combination of cultivation and amplicon sequencing. 109 fungal strains belonging to 30 mostly basidiomycetous species were isolated from glacial samples with counts up to 10³ CFU/100 ml. Glaciozyma-related taxon and Phenoliferia psychrophenolica were the dominant species. Unexpectedly, amplicon sequencing uncovered sequences of Chytridiomycota in all samples and Rozellomycota in sea water, lake water, and tap water. Sequences of Malassezia restricta and of the extremely halotolerant Hortaea werneckii were also found in subglacial habitats for the first time. Overall, the fungal communities within a glacier and among glaciers were diverse and spatially heterogenous. Contrary to this, there was a large overlap between the bacterial communities of different glaciers, with Flavobacterium sp. being the most frequently isolated. In amplicon sequencing Actinobacteria and Proteobacteria sequences were the most abundant.

Unconventional Cell Division Cycles from Marine-Derived Yeasts

Fungi have been found in every marine habitat that has been explored; however, the diversity and functions of fungi in the ocean are poorly understood. In this study, fungi were cultured from the marine environment in the vicinity of Woods Hole, MA, USA, including from plankton, sponge, and coral. Our sampling resulted in 35 unique species across 20 genera. We observed many isolates by time-lapse, differential interference contrast (DIC) microscopy and analyzed modes of growth and division. Several black yeasts displayed highly unconventional cell division cycles compared to those of traditional model yeast systems. Black yeasts have been found in habitats inhospitable to other life and are known for halotolerance, virulence, and stress resistance. We find that this group of yeasts also shows remarkable plasticity in terms of cell size control, modes of cell division, and cell polarity. Unexpected behaviors include division through a combination of fission and budding, production of multiple simultaneous buds, and cell division by sequential orthogonal septations. These marine-derived yeasts reveal alternative mechanisms for cell division cycles that seem likely to expand the repertoire of rules established from classic model system yeasts.

[First autochthonous case report of tinea nigra in Chile]

Tinea nigra is an infrequent superficial mycosis caused by the dematiaceous fungus Hortaea werneckii. It usually occurs in tropical coastal areas, with very few reports in South American countries with temperate climates, generally corresponding to infections imported by travelers. We present the case of a Chilean adult patient, with no previous history of recent trips, with clinical and microbiological background consistent with palmar tinea nigra, treated with oral itraconazole and topical sertaconazole with a favorable response. This article is the first case reported in Chile, of autochthonous origin.

The extremely halotolerant black yeast Hortaea werneckii - a model for intraspecific hybridization in clonal fungi

The polymorphic black yeast Hortaea werneckii (Capnodiales, Ascomycota) is extremely halotolerant (growth from 0 to 30% [w/v] NaCl) and has been extensively studied as a model for halotolerance in Eukaryotes for over two decades. Its most frequent sources are hypersaline environments and adjacent sea-water habitats in temperate, subtropical and tropical climates. Although typically saprobic, H. werneckii can also act as a commensal coloniser on human skin, causing tinea nigra on hands and soles. Here, we report that addition of NaCl to culture media expands the growth range of H. werneckii to 37 °C, which explains its colonisation of human skin, with its increased salinity. The morphological and physiological plasticity/ versatility of H. werneckii indicate that a species complex might be involved. This was investigated in this polyphasic taxonomic analysis based on the global diversity of H. werneckii strains collected from hypersaline environments, and from humans and animals. Analysis of D1/D2domains of 28S and internal transcribed spacer rDNA revealed 10 and 17 genotypes, respectively, that were not always compliant. The genotypes have global distributions. Human and environmental strains with the same genotypes are intermingled. Due to the limited number of phylogenetically informative characters in the ribosomal DNA dataset, the partial genes encoding for β-tubulin (BTB) and mini-chromosome maintenance protein (MCM7) were also sequenced. The use of these genes was hampered by ambiguous sequences obtained by Sanger sequencing, as a consequence of the diploid and highly heterozygous genome of many H. werneckii strains. Analysis of the BTB and MCM7 genes showed that in some cases two copies of the gene from the same genome are positioned in distant phylogenetic clusters of the intraspecific gene tree. Analysis of whole-genome sequences of selected H. werneckii strains generally confirmed the phylogenetic distances estimated on the basis of ribosomal genes, but also showed substantial reticulation within the phylogenetic history of the strains. This is in line with the hypothesis that the diploid genomes of H. werneckii were formed by hybridizations, which have sometimes occurred between relatively divergent strains.

In vitro activity of nine antifungal agents against a global collection of Hortaea werneckii isolates, the agent of tinea nigra

The in vitro susceptibility of molecularly identified Hortaea werneckii isolates (n = 37), the causative agent of tinea nigra, originating from clinical and environmental sources was determined for nine antifungal agents. Posaconazole had the lowest geometric mean minimum inhibitory concentration (GM MIC) (0.07 µg/mL), followed by voriconazole (0.13 µg/mL), isavuconazole (0.14 µg/mL), itraconazole (0.16 µg/mL), terbinafine (0.19 µg/mL) and amphotericin B (0.92 µg/mL). In contrast, fluconazole (14.56 µg/mL), caspofungin (2.41 µg/mL) and anidulafungin (1.42 µg/mL) demonstrated the highest GM MICs/MECs against H. werneckii.

Tinea nigra palmaris: a clinical case in a rural Ethiopian hospital

Tinea nigra is an infrequent, superficial fungal infection, mainly caused by Hortaea werneckii, which is still underreported in Ethiopia. An asymptomatic 62-year-old male patient sought a rural hospital of Ethiopia, showing dark plaques on the palms of both hands. A superficial mycosis was suspected and a direct light microscopic mycological examination from skin scrapings revealed short brownish hyphae. To our knowledge, this is the first case of tinea nigra from the Ethiopian highlands. This may be due to the actual rarity of the condition or to underreporting.

Global Molecular Diversity of the Halotolerant Fungus Hortaea werneckii

A global set of clinical and environmental strains of the halotolerant black yeast-like fungus Hortaea werneckii are analyzed by multilocus sequencing and AFLP, and physiological parameters are determined. Partial translation elongation factor 1-α proves to be suitable for typing because of the presence/absence of introns and also the presence of several SNPs. Local clonal expansion could be established by a combination of molecular methods, while the population from the Mediterranean Sea water also responds differently to combined temperature and salt stress. The species comprises molecular populations, which in part also differ physiologically allowing further diversification, but clinical strains did not deviate significantly from their environmental counterparts.

Indoor wet cells as a habitat for melanized fungi, opportunistic pathogens on humans and other vertebrates

Indoor wet cells serve as an environmental reservoir for a wide diversity of melanized fungi. A total of 313 melanized fungi were isolated at five locations in Guangzhou, China. Internal transcribed spacer (rDNA ITS) sequencing showed a preponderance of 27 species belonging to 10 genera; 64.22% (n = 201) were known as human opportunists in the orders Chaetothyriales and Venturiales, potentially causing cutaneous and sometimes deep infections. Knufia epidermidis was the most frequently encountered species in bathrooms (n = 26), while in kitchens Ochroconis musae (n = 14), Phialophora oxyspora (n = 12) and P. europaea (n = 10) were prevalent. Since the majority of species isolated are common agents of cutaneous infections and are rarely encountered in the natural environment, it is hypothesized that indoor facilities explain the previously enigmatic sources of infection by these organisms.

Skin Fungi from Colonization to Infection

Humans are exceptional among vertebrates in that their living tissue is directly exposed to the outside world. In the absence of protective scales, feathers, or fur, the skin has to be highly effective in defending the organism against the gamut of opportunistic fungi surrounding us. Most (sub)cutaneous infections enter the body by implantation through the skin barrier. On intact skin, two types of fungal expansion are noted: (A) colonization by commensals, i.e., growth enabled by conditions prevailing on the skin surface without degradation of tissue, and (B) infection by superficial pathogens that assimilate epidermal keratin and interact with the cellular immune system. In a response-damage framework, all fungi are potentially able to cause disease, as a balance between their natural predilection and the immune status of the host. For this reason, we will not attribute a fixed ecological term to each species, but rather describe them as growing in a commensal state (A) or in a pathogenic state (B).

Acral manifestations of fungal infections

Fungal infections, which are named according to the body site involved, can affect any skin area, the fingernails, or the toenails. Numerous fungal agents are responsible for both superficial and deep fungal diseases. Dermatophytes and Candida spp are the most common causative organisms on the surface of the hands, feet, and nails of patients with superficial fungal diseases; however, although deep fungal infections of the skin are less common compared with superficial fungal diseases, their incidence is increasing worldwide due to cross-border travel. Most superficial fungal diseases are diagnosed clinically, but sometimes direct microscopic examination with potassium hydroxide and fungal culture may be necessary for diagnosis, especially in patients suspected of having tinea incognito. In cases of superficial fungal infections except for onychomycosis and tinea incognito, topical treatments are usually sufficient and effective, but systemic treatments may be required in recalcitrant cases. Deep fungal diseases may resemble each other clinically; therefore, the organism must be identified with laboratory methods and should be treated for a long period. We review the most important clinical, diagnostic, and therapeutic aspects of fungal diseases. This paper covers fungal problems encountered both in hospitals and in general practice.

A case of Tinea nigra associated to a bite from a European rabbit (Oryctolagus cuniculus, Leporidae): the role of dermoscopy in diagnosis

We report a case of Tinea nigra in an adolescent living in Itapema, Santa Catarina, Brazil, who presented a hyperchromic macule on the palm of the left hand, close to another erythematous macule caused by a rabbit bite. The patient received guidance on accidents and animal bites and evolved well treated with topical butenafine for the dermatomycosis. The authors also highlight the efficacy of the dermoscopic exam in diagnosing Tinea nigra with animal bite lesions and other traumas.

Scanning electron microscopy of tinea nigra

Tinea nigra is a rare superficial mycosis caused by Hortaea werneckii. This infection presents as asymptomatic brown to black maculae mostly in palmo-plantar regions. We performed scanning electron microscopy of a superficial shaving of a tinea nigra lesion. The examination of the outer surface of the sample showed the epidermis with corneocytes and hyphae and elimination of fungal filaments. The inner surface of the sample showed important aggregation of hyphae among keratinocytes, which formed small fungal colonies. The ultrastructural findings correlated with those of dermoscopic examination - the small fungal aggregations may be the dark spicules seen on dermoscopy - and also allowed to document the mode of dissemination of tinea nigra, showing how hyphae are eliminated on the surface of the lesion.

Benign acquired superficial skin lesions of the hand

Numerous dermatologic conditions may be visualized by the hand surgeon during office hours, including when examining patients for an alternative chief problem. Although the primary focus of the visit may be unrelated to a skin lesion, it is important for the hand surgeon to be familiar with these lesions to address patient inquiries and determine which lesions may require some form of treatment. This article reviews some of the most common benign acquired superficial skin lesions of the hand. Particular attention will be paid to epidermal lesions, pigmented lesions, vascular lesions, dermal fibrous/fibrohistiocytic lesions, and infections that can be confused with skin neoplasms or tumor-like conditions. Diagnostic clues, including photographs, will be provided for each lesion described, as well as the recommended treatment.

Spontaneous cure in a case of Tinea nigra

The authors report a case (in Itajai, Santa Catarina State, Brazil) of tinea nigra in a 4-year-old female child which spontaneously healed. We discuss the clinical and epidemiological aspects of the mycosis and this rare case of spontaneous healing.

Coniosporium epidermidis sp. nov., a new species from human skin

Coniosporium epidermidis sp. nov. is described from a superficial skin lesion with blackish discolouration in an 80-yr-old Chinese patient. The species produces dark, thick-walled, inflated, reluctantly liberating arthroconidia without longitudinal septa. Sequences of the ribosomal operon, as well as of the translation elongation factor 1-α support its novelty. The species is found in a lineage basal to the order Chaetothyriales, amidst relatives from rock, but also species repeatedly isolated from human skin and nails and eventually causing mild cutaneous infections. Coniosporium epidermidis is consistently found on humans, either asymptomatic or symptomatic. The species indicates a change of life style towards human pathogenicity, which is a recurrent type of ecology in derived Chaetothyriales. Superficial and cutaneous infection by melanized fungi is a new category in dermatology.

Black yeast-like fungi in skin and nail: it probably matters

Black yeast-like fungi are rarely reported from superficial infections. We noticed a consistent prevalence of these organisms as single isolations from mycological routine specimens. To investigate the prevalence of black yeast-like fungi in skin, hair and nail specimens and to discuss the probability of these species to be involved in disease. Slow-growing black yeast-like fungi in routine specimens were prospectively collected and identified. A questionnaire regarding patient information was sent to physicians regarding black yeast-like fungus positive patients. A total of 20,746 dermatological specimens were examined by culture. Black yeast-like fungi accounted for 2.2% (n=108) of the positive cultures. Only 31.0% of the samples, culture positive for black yeast-like fungi were direct microscopy positive when compared with overall 68.8% of the culture positive specimens. The most prevalent species were Phialophora europaea (n=29), Coniosporium epidermidis (n=12), Ochroconis cf. humicola (n=6) and Cladophialophora boppii (n=4). These are not common saprobes and thus less likely to be coincidental colonizers. In 10/30 cases, discolouration of nail/skin had been noticed. A limited number of black yeast-like fungi were repeatedly isolated from routine specimens suggesting that they may play a role in superficial infections or as colonizers.

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Tinea versicolor, tinea nigra, white piedra, and black piedra

Superficial mycoses are fungal infections limited to the stratum corneum and its adnexal structures. The most frequent types are dermatophytoses or tineas. Tinea versicolor involves the skin in the form of hypochromic or hyperchromic plaques, and tinea nigra affects the skin of the palms with dark plaques. White piedra and black piedra are parasitic infections of scalp hairs in the form of concretions caused by fungal growth. Diagnosis of these mycoses is made from mycologic studies, direct examination, stains, and isolation, and identification of the fungi. Treatment includes systemic antifungals, topical antifungals, and keratolytics.