Tinea corporis bullosa

Atypical and Unpredictable Superficial Mycosis Presentations: A Narrative Review

While typically exhibiting characteristic features, fungal infections can sometimes present in an unusual context, having improbable localization (eyelid, face, or joint); mimicking other skin diseases such as eczema, psoriasis, or mycosis fungoides; and appearing with unexpected color, shape, or distribution. The emergence of such a challenging clinical picture is attributed to the complex interplay of host characteristics (hygiene and aging population), environment (climate change), advances in medical procedures, and agent factors (fungal resistance and species emergence). We aim to provide a better understanding of unusual epidemiological contexts and atypical manifestations of fungal superficial diseases, knowing that there is no pre-established clinical guide for these conditions. Thus, a literature examination was performed to provide a comprehensive analysis on rare and atypical superficial mycosis as well as an update on certain fungal clinical manifestations and their significance. The research and standard data extraction were performed using PubMed, Medline, Scopus, and EMBASE databases, and a total of 222 articles were identified. This review covers published research findings for the past six months.

[Report of the first case of tinea corporis bullosa by Trichophyton tonsurans]

Blister formation in tinea corporis is rare. Bullous tinea is usually evoked by zoophilic dermatophytes. A 20-year-old woman presented in our out-patient department with a painful pruritic bullous skin eruption at the left forearm. Clinically, a 4 × 3 cm symmetrical plaque with sharp borders and peripheral versiculation and serous crusts was seen. Histologically there was a marked spongiotic dermatitis with fungal elements in periodic acid stain (PAS). By fungal culture, PCR and gene sequencing Trichophyton (T.) tonsurans was identified. To the best of our knowledge, this is the first published case of T. tonsurans as the causative agent of bullous tinea corporis.

A Distinct Clinicopathological Presentation of Cutaneous Dermatophytosis Mimicking Autoimmune Blistering Disorder

Infectious diseases can clinically present as vesiculobullous disorders. Direct immunofluorescence (DIF) study of skin biopsy helps distinguish true autoimmune blistering disorders from other conditions. In many situations, even DIF findings in infections disorders imitate autoimmune process. Here, we describe a case of 29-year-old female with extensive dermatophytosis having presentation mimicking bullous pemphigoid both clinically and histopathologically including DIF findings.

The role of histopathology in the diagnosis of dermatophytoses / Značaj patohistološkog nalaza u dijagnostici dermatofitoza

Histopathological analysis is not a routine procedure for diagnosing fungal skin infections. In the histopathological specimens, fungi are visible only when using special stain such as periodic acid-Schiff (PAS). However, histopathological analysis may not be performed in small laboratories. Histopathological characteristics of fungal skin infections are not specific. In all skin biopsy cases, obtained without clinical suspicion of fungal infection, the knowledge of certain, most frequent histopathological reaction patterns, as well as specific histopathological indicators (a diagnostic histopathological “clue”), of certain superficial mycoses e.g., dermatophytoses, may raise a suspicion of fungal infection and warrant a fungal-specific staining. A retrospective analysis of all PAS-stained sections was carried out. All PAS-positive biopsy specimens were assessed for clinical features, histopathological patterns of skin reactions, and presence of histopathological indicators. Our results have shown that out of the total of 361 PAS-stained sections, fungal hyphae were identified in 12 (3.3%) specimens. In 5 (1.4%) cases, the diagnosis of fungal infection was suspected on clinical grounds, while in 7 (1.9%) cases detection of fungi was an unexpected finding. The most frequent type of histopathological pattern was spongiotic, and the most frequent histopathological indicator was the presence of neutrophils within the epidermis. Our results confirm that dermatophytoses may present with clinical and histological non-specific findings. PAS staining represents a relatively cheap and simple fungal-specific staining. It has been suggested that it not only confirms that the selected material is actually invaded, but also reduces the number of false-negative direct reports, where fungi are cultured from a microscopically negative specimen. Apart from a small percentage of positive findings, our results justify the need for routine PAS staining of all clinically and histologically non-specific inflammatory skin conditions.

Atypical manifestations of tinea corporis

Tinea corporis classically presents as an erythematous annular plaque with a scaly, centrifugally advancing border. However, sometimes vesicles and pustules are observed. Occasionally, even frank bullae appear secondary to severe inflammation. Diagnostic difficulties arise when atypical manifestations mimic other inflammatory skin diseases, including atopic or seborrheic dermatitis, subacute cutaneous lupus erythematosus, or vesicular diseases. We report five cases of atypical tinea corporis, where the initial clinical diagnosis was different from dermatophytosis. The differential diagnoses and the diagnostic difficulties related to atypical manifestations of fungal infections are discussed. Moreover, our cases emphasise the importance of conventional histological examination, which enables a fast, correct diagnosis.

Widespread tinea corporis caused by Trichophyton rubrum with non-typical cultural characteristics--diagnosis via PCR

From the epidemiological point of view, Trichophyton rubrum is the most important dermatophyte in the Western world. Mostly, the lesions of fungal infections of the skin are restricted and circumscribed. Immunodeficiency, diabetes or treatment with steroids, however, favour widespread disease involving the entire integument. In the present study, we describe a patient without immunodeficiency or diabetes presenting with widespread tinea corporis caused by T. rubrum. The fungal isolate showed atypical morphological features. Moreover, the typical metabolic features (negative urease test, production of red pigment on potato dextrose agar) were expressed with delay after 6 weeks of cultivation. Thus, sequencing of the internal transcribed spacer of the ribosomal DNA was applied to identify the fungal isolate and led us to the correct diagnosis, before conventional mycological methods were successful.

A virulent genotype of Microsporum canis is responsible for the majority of human infections

The zoophilic dermatophyte speciesMicrosporum canisbelongs to theArthroderma otaecomplex and is known to mate with tester strains of that teleomorph species, at least in the laboratory. Human infections are likely to be acquired from the fur of cats, dogs and horses. Epidemiological studies to reveal sources and routes of infection have been hampered by a lack of polymorphic molecular markers. Human cases mainly concern moderately inflammatory tinea corporis and tinea capitis, but, as cases of highly inflammatory ringworm are also observed, the question arises as to whether all lineages ofM. canisare equally virulent to humans. In this study, two microsatellite markers were developed and used to analyse a global set of 101M. canisstrains to reveal patterns of genetic variation and dispersal. Using a Bayesian and a distance approach for structuring theM. canissamples, three populations could be distinguished, with evidence of recombination in one of them (III). This population contained 44 % of the animal isolates and only 9 % of the human strains. Population I, with strictly clonal reproduction (comprising a single multilocus genotype), contained 74 % of the global collection of strains from humans, but only 23 % of the animal strains. From these findings, it was concluded that population differentiation inM. canisis not allopatric, but rather is due to the emergence of a (virulent) genotype that has a high potential to infect the human host. Adaptation of genotypes resulting in a particular clinical manifestation was not evident. Furthermore, isolates from horses did not show a monophyletic clustering.

Tinea manuum bullosa

We report a case of tinea manuum bullosa in a 36-year-old male, a crop and livestock farmer by trade. The lesion, resembling contact dermatitis, was located in the palm of the right hand. We isolated Trichophyton verrucosum. No other skin lesion was detected. Blood chemistry and immunology test results were normal. Treatment with terbinafine 250 mg day(-1) led to clinical and mycological healing.

Subtle intracorneal findings in inflammatory disorders: hyphae or not?

BACKGROUND

Spongiotic and lichenoid dermatitides are frequently stained with periodic acid-Schiff (PAS) stains to check for the presence of dermatophytes. PAS+ structures without a septate morphology are often seen with lichenoid dermatitides, however, their nature has not been previously characterized.

METHODS

Fifteen consecutive biopsies of lichenoid and five spongiotic dermatitides were stained with hematoxylin and eosin (H&E), PAS, and antibodies to CD1a.

RESULTS

Twelve of 15 lichenoid and none of the five spongiotic dermatitis showed PAS+ structures in the stratum corneum. Distinct septation or branching was not identified in these PAS+ structures. Eleven of 15 from the lichenoid group, but none from the spongiotic group, showed CD1a+ structures in the stratum corneum. This staining pattern suggests that the intracorneal structures represent the dendritic processes of Langerhans' cells (LCs) within the stratum corneum.

CONCLUSIONS

PAS+ and CD1a+ structures are present in the stratum corneum of lichenoid, but not in spongiotic, dermatitis. This study morphologically confirms extension of LC dendrites into the stratum corneum in lichenoid but not in spongiotic dermatitides.

The periodic acid-Schiff stain in diagnosing tinea: should it be used routinely in inflammatory skin diseases?

BACKGROUND

The clinical presentation of tinea is usually, but not always, characteristic. The purpose of this study was to determine whether the routine use of the periodic acid-Schiff (PAS) stain in inflammatory skin disorders is requisite for identifying clinically undiagnosed tinea cases and to ascertain whether there are histopathologic clues that suggest the diagnosis of a dermatophyte infection.

METHODS

Hematoxylin and eosin (H&E)-stained slides from 60 PAS-positive tinea cases were examined histologically by two observers. One observer, aware of the diagnosis of tinea, searched for hyphal elements and also recorded in detail epidermal, dermal, and follicular changes. The second observer, not aware of the diagnosis beforehand, reviewed the same slides, together with randomly mixed slides from 21 non-tinea cases, recording the same parameters as the first reviewer.

RESULTS

Of the 60 cases of tinea, only 45% were diagnosed clinically. Histologic examination of H&E sections by the two observers disclosed the presence of hyphal elements in 68 and 45%, respectively. No significant histologic differences, except for the presence of hyphae, were observed between tinea and non-tinea cases.

CONCLUSIONS

The finding that only 57% of PAS-positive cases of tinea showed hyphal elements on H&E examination alone, together with no other differentiable histologic characteristics, lends strong support for the routine use of PAS-staining for inflammatory skin disorders.

Tinea corporis, tinea cruris, tinea nigra, and piedra

Tinea infections are among the most common dermatologic conditions throughout the world. To avoid a misdiagnosis, identification of dermatophyte infections requires both a fungal culture on Sabouraud's agar media, and a light microscopic mycologic examination from skin scrapings. Topical antifungals may be sufficient for treatment of tinea corporis and cruris and tinea nigra, and the shaving of hair infected by piedra may also be beneficial. Systemic therapy, however, may be required when the infected areas are large, macerated with a secondary infection, or in immunocompromised individuals. Preventative measures of tinea infections include practicing good personal hygiene; keeping the skin dry and cool at all times; and avoiding sharing towels, clothing, or hair accessories with infected individuals.