Clinical profile of Tinea pseudoimbricata: an observational study from a tertiary care institution in western Maharashtra, India

INTRODUCTION

Superficial dermatophytoses has been on splurge in the past few years, accounting for approximately 50% of patients visiting dermatology OPD. There is unrestricted availability of over-the counter potent and super-potent topical steroids (alone or in combination with antifungals and antibiotics, leading to evaluation of atypical presentation of dermatophytosis, which is termed as tinea incognito. Tinea pseudoimbricata is thus named as it simulates tinea imbricata, with features of concentric rings, caused due to trichophyton concentricum. T. pseudoimbricata has morphologic similarity to T. imbricata but is not caused due to T. concentricum. It is often seen in immunocompromised hosts or in patients with history of steroid abuse. This condition has been postulated to occur as a result of local immunosuppression induced by topical steroids.^1,2 This case series presents clinic-epidemiological and dermoscopic characteristics of this dermatophytoses.

METHODS

This was a cross-sectional study conducted in the department of dermatology, Dr. D Y Patil Medical College and Hospital, Pune from September 2017 to September 2019. A total of 185 patients of tinea incognito were diagnosed out of which 77 patients with the clinical diagnosis of T. pseudoimbricata were found. Potassium hydroxide (KOH) examination of skin scraping and culture was performed. A detailed history pertaining to the use of topical formulation (name and contents were ascertained either on seeing the tubes used or from the prescription), duration and frequency of application, and information about the source of prescription was noted. Skin scraping from the lesions was used for direct microscopic examination in 10% KOH and for culture on the Saboraud's dextrose agar (SDA) with cycloheximide and chloramphenicol. Dermoscopy was done using the universal serial bus dermatoscope. The data was entered in Microsoft Excel and statistical analysis was done using “Epi Info 7” Software.

RESULTS

The mean age of the 77 patients was 28.66 (±18.3) years. There were fifty two males and twenty five females. The mean disease duration was 7.6 (±12.7) months. All patients gave history of using potent and super-potent topical steroids; topical steroid had been used in combination with antifungals like miconazole, clotrimazole, and terbinafine, antibiotics like ornidazole, ofloxacin in varying combinations 57.14%, clobetasol proprionate (0.05%) was used by 11 out of 77 patients (14.28%), betamethasone diproprionate by 17 patients (22.07%), mometasone furoate by 5 patients.(6.49%). About 35 out of 77 (48.05%) patients had done self-medication on suggestion from friends and family while steroid combination was prescribed by chemist in 30 (38.96%) and by unqualified registered medical practitioners in 12 (15.58%). None of the patients had visited a dermatologist for the treatment of their skin disease.

All patients presented with multiple (>2) concentric erythematous rings that was associated with moderate-to-severe pruritus (Figure 1 a-d). Scaling was seen in 45 patients (58.44%).

The most common clinical presentation was Tinea corporis (86.33%) followed by Tinea cruris (11%) and Tinea faciei (2.67%). KOH examination showed hyaline, long, branching septate hyphae in all the patients. The demographic, clinical, and mycological details are summarized in (Figure 2). Patients with T. mentagrophytes had a more widespread and multiple site infection as compared to T. rubrum. The inflammation and chronicity of the lesions were again greater in T. mentagrophytes.

Dermoscopy was done for all the patients and the most recent concentric lesion was chosen to document the dermoscopic features. Dermoscopy revealed background erythema; with dilated linear, tortous, and/or dotted vessels; peripheral whitish scales; micropustules at the borders; Tinea of villous hairs; reddish brown hemorrhagic spots at the periphery.

DISCUSSION

Tinea imbricata is a superficial mycosis caused by T. concentricum with a characteristic pattern of concentric and/or annular plaques of erythema and scales. ‘Imbrex’( latin) means overlapping roof tiles.³ T. pseudoimbricata is thus called because it simulates but caused by species other than T. concentricum. T. pseudoimbricata has been caused by Trichophyton tonsurans, T. rubrum, T. mentagrophytes, Microsporum audouinii, and Microsporum gypseum.⁴

Most of our patients were young to middle-aged females. History of potent topical steroid application steroids prior to appearance of lesions was present in all our patients. Our findings of this demographic data is similar to the finding by Singal et al, Verma et al, Verma et al, Jakhar et al and Kakkar et al.^4-8 This suggests that many women are seeking treatments in order to have fair skin. Lack of resources, wrong notion among the general population and especially the pharmacists that steroid application helps in brightening of skin, supply of drugs by pharmacists without prescription has lead to steroid misuse.

All our patients presented with multiple concentric or annular erythematous scaly plaques. Diagnosis was made visually by appearance of "ring-within-a-ring" lesions, similar to the study by Sonthalia et al.¹ Fungal culture in our patients revealed T. rubrum to be the predominant species.

Dermatophyte invasion of the skin is caused by the activation of specific genes which produce antigens such as proteinases. Both innate (e.g. b-defensins) and acquired T cell-mediated immunity is responsible for erythema and scaling. In T. concentricum infections, genetically determined variations led to weak expression of acquired immunity of dermatophyte modulation. The classic appearance of tinea is suppressed due to the anti-inflammatory effect of topical steroids. Erratic use of topical steroids leads to periods of active inflammation and apparent remission with the appearance of multiple rings and inadequate clearing of the fungus.^5,6

A ring effect similar to that described here can be explained by the fact that although host reaction occurs in response to actively metabolizing fungal cells, these are only partially inhibited as a result of concomitant topical steroid treatment. When local immune responses decline below a key threshold, the fungal genes are switched on again and instigate another zone of host-induced inflammatory response. This may be repeated several times, resulting in concentric rings of scaling and inflammation that reflect the alternating activation and deactivation of defense mechanisms. The more widely known result of the unrestricted application of topical corticosteroids in dermatophytosis is Tinea incognito. However, the injudicious use of topical preparations containing steroids is also responsible for development of the distinct clinical presentation of Tinea pseudoimbricata. We examined other sites for fungal infection, such as beneath the breasts in women, soles of the feet, and nails. We confirmed the diagnosis of Tinea by examining a skin scraping in 10% potassium hydroxide under a microscope for hyphae and spores of dermatophytes. Fungal culture was also performed in few patients.

All lesions were thoroughly examined under dermascope. As in the article by Jakhar et al, dermoscopy showed the presence of background erythema with dilated linear, tortous, and/or dotted vessels, which may point toward the possible topical steroid abuse.⁷ Also, the polygonal arrangement of these vessels may point toward the chronicity of topical steroid abuse.⁷ In addition, we suggest that the presence of micropustules at the periphery indicate disease activity while the brownish hemorrhagic spots may indicate the excoriation marks secondary to pruritus. Dermoscopy may serve as a quick and non-invasive tool for identification of cases with topical steroid abuse.

Systemic antifungal is mandated in such situations for a prolonged period of at least 6 to 8 weeks. The prognosis is good if the patient adheres to the treatment and further steroid abuse is halted. It is of equal importance to treat the family members to decrease the chances of reinfection and to counsel regarding the separate washing of infected clothes and avoidance of sharing of towels, clothes, bed linen, and soaps.

ACKNOWLEDGEMENTS

We would like to thank Department of Dermatology and Department of Microbiology, Dr. D.Y. Patil medical College and Hospital, Pune.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: The study was approved by the institutional ethics committee

REFERENCES

1. 1. Sonthalia S, Singal A, Das S. Tinea cruris and tinea corporis masquerading as tinea indecisiva: Case report and review of the literature. J Cutan Med Surg. 2014;18:1-6.
2. 2. Batta K, Ramlogan D, Smith AG, Garrido MC, Moss C. ‘Tinea indecisiva’ may mimic the concentric rings of tinea imbricata. Br J Dermatol. 2002;147:384.
3. 3. Lim SP, Smith AG. “Tinea pseudoimbricata”: Tinea corporis in a renaltransplant recipient mimicking the concentric rings of Tinea imbricata. Clin Exp Dermatol. 2003;28:332-3.
4. 4. Singal A, Jakhar D, Kaur I, Pandhi D, Das S. Tinea pseudoimbricata as a unique manifestation of steroid abuse: A clinico-mycological and dermoscopic study from a tertiary care hospital. Indian Dermatol Online J 2019;10:422-5.
5. 5. Verma S, Hay RJ. Topical steroid-induced Tinea pseudoimbricata: A strikingform of tinea incognito. Int J Dermatol. 2015;54:192-3.
6. 6. Verma SB, Zouboulis C. Indian irrational skin creams and steroid-modified dermatophytosis-an unholy nexus and alarming situation. J Eur Acad Dermatol Venereol. 2018;32:426-7.
7. 7. Jakhar D, Kaur I. Dermoscopy of topical steroid damaged/dependent face. Indian Dermatol Online J. 2018;9:286-7.
8. 8. Kakkar S, Sharma PK. Topical steroid-dependent face: Response to xylometazoline topical. Indian J Drugs Dermatol. 2017;3:87-9.