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

Majocchi's granuloma-A multicenter retrospective cohort study

Background

Majocchi's granuloma (MG) is an uncommon deep fungal folliculitis predominantly caused by dermatophytes. Given the rarity of this condition, available data regarding predisposing comorbidities/risk factors, clinical characteristics, offending microbiologic pathogens, diagnostics, pathologic findings, and treatment approaches has been inferred from historical cases.

Objectives

To review our institutional experience with MG.

Methods

We retrospectively analyzed a multicenter cohort of adult patients diagnosed with MG between 1992 and 2022.

Results

We analyzed 147 patients with MG, 105 of which were male with a median age of 55.6 years. Immunosuppressant and topical corticosteroid use were common prior to development of MG. Dermatologic lesions and their sites of involvement did not differ based on the immune status of patients. Trichophyton rubrum was the most common causative pathogen of MG, in addition to other dermatophytes. Treatment duration for all prescribed agents was median 31.5 days with oral terbinafine being the most frequently utilized agent. Clinical resolution was achieved in 96.6% of cases.

Limitations

Retrospective, nonrandomized study.

Conclusions

Although rare and clinically variable in presentation, diagnosis of MG often requires histopathologic confirmation to subsequently direct prolonged treatment with systemic antifungal therapy for mycological cure.

Preordering Periodic Acid-Schiff Staining: A Quality Improvement Study

ABSTRACT

Periodic acid-Schiff (PAS) stain is a commonly used ancillary test for inflammatory and infectious dermatoses, yet infrequently changes the diagnosis. Previous studies have shown that clinical suspicion and histopathologic features are poor predictors of PAS positivity. Current appropriate use criteria from the American Society of Dermatopathology supports PAS staining when histopathologic features could be consistent with a dermatophyte infection. At the authors' institution, PAS stains are preordered on biopsies of inflammatory and infectious diagnoses to aid in a timelier sign out. Our aim was to reduce the percentage of PAS stains preordered on all dermatology specimens over a 6-month period without reducing the percentage of fungal infections identified. Review of a 12-month preintervention period found that our laboratory received 6104 biopsies for which PAS stain was preordered on 616 (10.1%). Based on a review of the preintervention period, preordering PAS on cases with clinical suspicion for cutaneous T-cell lymphoma was stopped unless there was clinical suspicion for eczematous dermatitis, vesiculobullous disorders, or fungal infection. The proposed intervention resulted in a 3.7% reduction in the number of PAS stains ordered while PAS-positivity rate remained unchanged. The described quality improvement process may be used as a model for other laboratories.

A Clinico-Mycological and Histopathological Study of Recurrent Dermatophytosis

Background

A few recent studies have shown fungal elements within the hair follicle epithelium, which may act as a reservoir and responsible for recurrent dermatophytosis.

Objectives

To assess the clinical patterns, mycological profile, and histopathology of recurrent dermatophytosis and to determine the prevalence of fungal hyphae in the hair follicle epithelium and other appendages.

Materials and Methods

One hundred and fifty clinically diagnosed cases of recurrent dermatophytic infection were included. Skin samples were taken for direct microscopy, fungal culture, and histopathological analysis. Haematoxylin and eosin and special staining with periodic acid Schiff (PAS) and Gomori's methenamine silver (GMS) were performed to detect the fungal hyphae in the skin and hair follicle epithelium.

Results

The most common clinical pattern observed was tinea corporis et cruris in 64 patients (42.66%). On direct microscopy and fungal culture, positive results were obtained in 116 cases (77.33%) and 78 (52%) cases, respectively. Presence of fungal hyphae in the stratum corneum, hair follicle, and acrosyringium was seen in 107 patients (71.33%), 47 patients (31.33%), and five patients (3.33%), respectively. Out of the 52 cases with hair follicle and eccrine gland involvement, history of fixed drug combinations (FDC) cream use was present in 42 cases (80.76%) and absent in ten cases (19.24%) (P = 0.000062).

Limitations

Skin samples were taken only from a single skin lesion. Higher incidence of follicular invasion may have been detected if multiple biopsy samples were taken.

Conclusion

Hair follicle/eccrine sweat gland involvement was observed in nearly one-third of the patients, which may act as a reservoir and may be responsible for recurrence and chronicity. Histopathology should be considered as an important adjuvant tool in recurrent dermatophytosis to establish the extent of the infection, which guides the further management.

What Percentage of Hairs Are Infected in Biopsies of Fungal Folliculitis?

Fungal folliculitis (including tinea capitis and Majocchi granuloma) has a wide range of clinical presentations, and biopsy may be obtained to distinguish this from other conditions with similar presentations. The study aims to evaluate the proportion of hairs infected in biopsies of fungal folliculitis. Copath records were searched for diagnoses of fungal folliculitis, tinea capitis and Majocchi granuloma between 1 January 2000 and 31 December 2020. Confirmed cases were pulled and reviewed by a dermatopathologist to count the total number of hairs on the sample and the total infected. Of 72 included cases, the median number of hair follicles per biopsy was 3 (IQR 1,4), and the median proportion of hairs infected was 54.2% (IQR 33.3%, 100.0%). Nineteen (26.4%) had only one hair included in the biopsy which was also an infected hair (100% of hairs were infected). The percentage of total hair follicles infected differed significantly depending upon location (p = 0.0443), with a smaller percentage of infected hairs in biopsies of tinea capitis. Clinicians should be cautious when using biopsy for diagnosis of fungal folliculitis, specifically, when there are few hairs in the specimen. Failure to capture infected hairs leads to false negative diagnoses.

Updates and Proposed Diagnostic Approach to Psoriasiform Dermatoses

Psoriasiform dermatoses represent a wide array of skin diseases commonly encountered by clinicians and pathologists. While they may present a diagnostic challenge, thorough observation coupled with proper interpretation of subtle additional clinical or histopathologic features provide clues to the correct diagnosis. In this review, we provide updates on emerging entities and develop a systemic approach to establish the pathologic diagnosis, with emphasis on the importance of clinicopathologic correlation.

Tinea Gladiatorum: Epidemiology, Clinical Aspects, and Management

Tinea gladiatorum (TG) is a fungal skin infection that occurs among wrestlers and other contact sport athletes with a varied prevalence rate. The most common causative factor responsible as well for local outbreaks of the infection is an anthropophilic dermatophyte species—Trichophyton tonsurans (T. tonsurans). The purpose of this study was to gather current data about TG, including epidemiology, possible diagnosing methods, clinical features, treatment approaches, and potential prevention techniques. We also performed a systematic review of studies describing TG incidence. The prevalence of the disease varied from 2.4% up to 100%. That wide range of variability forces medical practitioners to update knowledge about TG and points to the fact that it still may be a diagnostic and therapeutic challenge. Spreading awareness among athletes and trainers is one of the most important preventive steps.

Histopathological Findings in Nail Clippings With Periodic Acid-Schiff-Positive Fungi

BACKGROUND

Periodic acid-Schiff (PAS) staining of nail clippings is an adjunct diagnostic tool for onychomycosis.

OBJECTIVE

To detect histopathological findings as clues to the presence of PAS-positive (+) fungal elements in nail clippings.

METHODS

Four hundred sixteen consecutive nail clippings suspected of onychomycosis were stained with hematoxylin and eosin, and with PAS stains. All cases were studied histopathologically. The clinical files of the cases with neutrophils were reviewed.

RESULTS

PAS+ staining for fungi were demonstrated in 159 (38%) of the nail clippings. Neutrophils, parakeratosis, plasma globules, and bacteria were observed in 43 (27%), 108 (67%), 80 (50%), and 80 (50%) of the PAS+ cases, respectively, and in 17 (6%), 109 (41%), 84 (32%) and 140 (54%) of the PAS- cases, respectively (P < 0.01). Neutrophils showed by far the highest specificity (93%), although with low sensitivity (27%) for the presence of PAS+ fungi. Among the 43 PAS+ and 17 PAS- specimens with neutrophils, only 1 (2.3%) and 3 (17%) had overt psoriasis, respectively.

CONCLUSION

Neutrophils in nail clippings may serve as a clue for onychomycosis. PAS staining with neutrophils is not necessarily associated with psoriasis.

Pathophysiology of psoriasis: A review

Psoriasis is a complex chronic inflammatory skin disease caused by the dynamic interplay between multiple genetic risk foci, environmental risk factors, and excessive immunological abnormalities. Psoriasis affects approximately 2% of the population worldwide, and dramatic advances have been achieved in the understanding and treatment options for psoriasis. Recent progress in biological therapies has revealed the fundamental roles of tumor necrosis factor-α, interleukin (IL)-23p19, and the IL-17A axis together with skin-resident immune cells and major signal transduction pathways in the pathogenesis of psoriasis. In addition to IL-17-producing T helper17 cells, innate lymphoid cell (ILC)3 induces psoriasis rashes directly without T-cell/antigen interaction in response to the released antimicrobial peptides from activated keratinocytes and inflammatory cytokines. ILC3 typically expresses retinoic acid receptor-related orphan receptor gamma t in the nucleus, matures in the presence of IL-7 and IL-23, and produces IL-17 and IL-22. The number of ILC3s is increased in the blood, psoriasis rash, and even in nonrash areas of psoriatic skin. Psoriasis is significantly associated with cardiovascular disease, metabolic syndrome, and inflammatory disorders, particularly the severe type. The similarity of enterobacteria in the psoriasis gut to that in diabetic patients may be related to its pathogenesis. In the current review, we focus on the pathophysiology of psoriasis in the accelerated immunological inflammatory loop, danger signal from keratinocytes, and cytokines, particularly IL-17 and IL-23p19. In addition, pathophysiological speculation with regard to morphology has been supplemented. Finally, the differences and similarities between psoriasis and atopic dermatitis are discussed.

PAS and GMS utility in dermatopathology: Review of the current medical literature

The American Society of Dermatopathology has established an Appropriate Use Criteria (AUC) Committee with the intention of establishing evidence-based recommendations regarding the appropriateness of various ancillary tests commonly utilized by dermatopathologists. Periodic acid Schiff (PAS) and Grocott (or Gomori) methenamine silver (GMS) stains represent some of the most commonly employed ancillary tests in dermatopathology. The utility of these tests was targeted for evaluation by the AUC. This literature review represents a comprehensive evaluation of available evidence for the utility of PAS and/or GMS staining of skin and nail biopsies. In concert with expert opinion, these data will be incorporated into future recommendations by the AUC for PAS and GMS staining in routine dermatopathology practice.

Histopathology of Hair Follicle Epithelium in Patients of Recurrent and Recalcitrant Dermatophytosis: A Diagnostic Cross-Sectional Study

Context:

Recurrent and recalcitrant dermatophytosis is a major evolving health problem in India. Histopathology is important in the diagnosis of recurrent and resistant cases, as it is postulated that hair follicle epithelium is affected, acting as the reservoir leading to recurrence and recalcitrance.

Aims:

This study aims to study histopathology of hair follicle epithelium in patients of recurrent and recalcitrant dermatophytosis.

Settings and Design:

A diagnostic cross-sectional study was performed at tertiary care hospital and referral center in central India.

Materials and Methods:

A 3 mm-sized punch skin biopsy was taken from 108 patients of recurrent or recalcitrant dermatophytosis involving hair follicles. Sections were stained by hematoxylin and eosin (H and E) stain in these patients followed by special stains such as periodic acid–Schiff (PAS) stain and Gomori methenamine silver (GMS) stain in 78 individuals where hair follicle was seen on H and E stain.

Results:

In H and E stain, surface epidermis fungus was observed in 57/108 patients (52.7%). In hair follicle-positive sections (78), surface fungus was seen in 52.6% with H and E stain, 84.6% with PAS stain, and 91% with GMS stain. H and E was 62.12% sensitive and 100% specific to diagnose fungus when compared with PAS stain and 57.7% sensitive and 100% specific when compared with GMS stain. PAS was 91.5% sensitive and 85.7% specific when compared with GMS stain. Ectothrix infection was the most common form of hair infection observed in 87.2% cases with GMS stain. Simultaneous presence of fungus in hair follicle and stratum corneum was observed in 87.3% of patients.

Conclusion:

Majority of patients showed affection of hair follicles by dermatophytes in clinically chronic, recurrent, and recalcitrant dermatophytic infections. GMS stain is the acceptable gold standard for detection of fungal elements.

Majocchi's granuloma: current perspectives

Majocchi’s granuloma (MG) is a rare fungal infection of the dermis that is mainly caused by dermatophytes (in ≥95% of cases); the most frequently identified cause is anthropophilic Trichophyton rubrum. In the rest of the cases, the causes are non-dermatophytic fungi such as Aspergillus species. This review aimed to provide information about the current perspectives on MG regarding its clinical characteristics, predisposing factors, laboratory diagnosis, and treatment strategies. Although the lower extremities were reported to be the most common site of infection, facial involvement has been predominant in the past 5 years. Our literature research showed that the most common predisposing factor (55%) is the use of topical steroid creams without potassium hydroxide examination during treatment of erythematous squamous dermatoses. A reliable diagnosis of MG is based on histopathological examination, including fungal culture and molecular analyses. MG should be treated not only with topical agents but also with systemic antifungal agents that are continued until the lesions are completely resolved. In systemic treatment, the most preferred drug is terbinafine, because of its efficacy, side effects, and safety.

Can Routine Histopathology Distinguish Between Vulvar Cutaneous Candidosis and Dermatophytosis?

OBJECTIVES

This study aimed to determine if vulvar cutaneous candidosis and dermatophytosis can be distinguished by routine histopathology.

MATERIALS AND METHODS

Twenty-four cases of periodic acid-Schiff-stained vulvar biopsies with a diagnosis of cutaneous mycosis were reviewed and histopathological characteristics on both periodic acid-Schiff and hematoxylin and eosin were recorded. Data were collected on age, clinical impression, microbiological results, and treatment, and all specimens underwent multiplex polymerase chain reaction analysis.

RESULTS

The mean age was 60 years, and all but 3 women had at least 1 risk factor for mycosis including 15 (62.5%) with lichen sclerosus and/or planus managed with topical corticosteroids. A clinical suspicion of tinea or candidosis was documented in 12 (50%) of the cases. Vulvovaginal swabs showed Candida species in 9 women; one skin scraping was positive for Trichophyton rubrum. Microbiology was not obtained in 8 patients, 5 had a negative swab, and 1 had negative skin scrapings. No histopathological or morphological features distinguished Candida species from dermatophytes. Organisms appeared as basophilic structures in the stratum corneum in 15 (62.5%) hematoxylin and eosin-stained slides. Polymerase chain reaction results were positive for Candida species in 5 (21%) and for dermatophytes in 3 (13%), negative in 13, and unassessable in 3 cases.

CONCLUSIONS

Vulvar cutaneous candidosis and dermatophytosis cannot be reliably distinguished by routine histopathology or specific polymerase chain reaction. A high index of suspicion combined with adequate microbiological testing remains the best approach to differentiating between the 2, which impacts on counseling, treatment, and prognosis.

'Hints' in the horn: diagnostic clues in the stratum corneum

The stratum corneum or horny layer is the uppermost layer of the epidermis, and is mainly responsible for the skin's barrier function. In spite of its complexity at the ultrastructural and molecular level, the features accessible to visualization on conventional histology are relatively limited. Nevertheless, knowledge of subtle clues that one may observe in the stratum corneum can prove useful in a wide range of situations in dermatopathology. We herein review a selection of common and rare entities in which the horny layer may reveal significantly important hints for the diagnosis. These clues include parakeratosis and its different patterns (focal, confluent, alternating, associated with spongiosis, epidermal hyperplasia or lichenoid changes), subcorneal acantholysis, infectious organisms in the stratum corneum (including fungal, bacterial and parasitic), thickening or thinning of the stratum corneum and the presence of different kinds of pigment. Even when normal, the horny layer may prove to be useful when seen in association with severe epidermal damage, a combination of features testifying to the acute nature of the underlying pathological process.

Polycyclic Annular Lesion Masquerading as Lupus Erythematosus and Emerging as Tinea Faciei Incognito

Tinea incognito is a dermatophytic infection induced by immunosuppressive agents that lacks the classic features of a typical fungal infection. Although the treatment of tinea incognito is simple and relatively easy, its clinical manifestation varies and can masquerade as various skin disorders, causing misdiagnosis and thus preventing prompt and appropriate treatment. Here, we report an interesting case of tinea incognito occurring after topical steroid administration in an immunosuppressed patient with dermatitis artefacta. A 40-year-old female patient who had been taking systemic glucocorticoid for 4 years for chronic inflammatory demyelinating polyneuropathy presented with itching multiple erythematous erosive lesions on the face and upper chest for 2 months. Initial biopsy produced nonspecific findings. The skin lesion was aggravated and became polycyclic and erythematous; after azathioprine was added, her chronic inflammatory demyelinating polyneuropathy became aggravated. A second biopsy confirmed hyphae in the cornified layer. Complete remission was achieved after admonishing oral terbinafine and topical amorolfine.

The routine use of iron stain for biopsies of dermatoses of the legs

BACKGROUND

Our goal was to study the utility of the routine use of the Gomori iron stain in the evaluation of leg biopsies of inflammatory lesions.

METHODS

One hundred consecutive skin biopsies from the legs were evaluated with hematoxylin and eosin and Gomori iron stains. Iron positivity was semi-quantitatively graded from trace to 4+.

RESULTS

Forty-two (42) cases were positive with the Gomori iron stain as follows: stasis dermatitis (14), Schamberg's disease (7), folliculitis (2), psoriasis (2), trauma (2), arthropod bite (2), allergic contact dermatitis (2), lichen simplex chronicus (1), senile purpura (1), vascular ectasia (1), lobular capillary hemangioma (1), scar (1), pretibial pigmented patches (1), tinea (1), lentigo maligna (1), traumatic fat necrosis (1), lichen planus (1) and fixed drug eruption (1). Twelve of 14 cases of stasis dermatitis had 2+ or greater iron staining; 8 cases were 3+ or 4+. All other diagnoses had trace or 1+ staining for iron except for one scar (2+). One of 19 samples (5.3%) of 'normal' leg skin controls showed iron stain positivity, and was graded as trace.

CONCLUSIONS

After correcting for iron staining in 5.3% of normal leg skin controls, we observed Gomori iron positivity in 36.7% of 100 consecutive leg biopsies. We suggest that routine application of an iron stain on biopsies of dermatoses from the legs is useful. Stasis dermatitis and Schamberg's disease are the most frequent iron positive diagnoses, and the diagnosis is aided by the pattern of hemosiderin deposition. Negative iron stain is also useful in suggesting the presence of melanin pigment in macrophages in lichenoid and other dermatoses. To confirm a truly negative iron stain, study of the section at ×400 rather than ×100 is recommended.

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.

Prominent papillary dermal edema in dermatophytosis (tinea corporis)

BACKGROUND

Commonly described histologic 'clues' to the diagnosis of dermatophytosis include neutrophils in the stratum corneum and/or epidermis, compact orthokeratosis and identification of fungal hyphae between two zones of cornified cells. Prominent (striking) papillary dermal edema (PPDE) is not commonly reported with dermatophytosis (tinea corporis).

METHODS

We observed an index case in which PPDE was the salient histologic finding in lesions of tinea corporis. Fifteen additional cases of tinea corporis with PPDE were diagnosed in our dermatopathology laboratory over a 9-year period. The clinical and histologic findings were reviewed.

RESULTS

All 16 cases occurred on the extremities of women, 11 of whom had skin of color. The submitted clinical differential diagnoses varied widely, but included some of the diseases 'classically' associated with PPDE, as well as other blistering eruptions. In several cases, only a few dermatophyte hyphae were identified in tissue sections.

CONCLUSIONS

Our case series serves as a reminder that dermatophytosis should be strongly considered in the differential diagnosis of lesions with PPDE. Fungal culture may be helpful in patients whose biopsies show PPDE, negative periodic acid-Schiff (PAS) stains and who fail to respond to conventional anti-inflammatory therapy. This study lends support for the routine use of PAS stains in biopsies of inflammatory dermatoses.

Histologic mimickers of mycosis fungoides: a review

Mycosis fungoides (MF) is a rare type of non-Hodgkin's lymphoma affecting the skin. Because MF develops slowly over several years and may have a variety of clinical presentations, including itchy patches, plaques or tumors that may be confused with common benign conditions such as eczema and psoriasis, the disease presents a diagnostic challenge. The average time to diagnosis varies but is frequently as long as 3 to 6 years. Skin biopsies frequently reveal non-specific features of several dermatoses; thus, histologic evaluation of the disease is also challenging. Importantly, various significant and/or benign conditions may mimic MF histologically and result in a misdiagnosis of MF. Here we review the reported histologic mimickers of MF and discuss both similar and differentiating features of each, in order to aid in more accurate interpretation of diagnostically challenging skin biopsies. Clinicopathologic correlation is ultimately essential to make accurate diagnosis of MF and its histologic mimickers.

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.