Tinea incognito also known as steroid-modified tinea are dermatophytic infections modified by the use of topical or systemic corticosteroids prescribed for a pre-existing pathology. This term can also include dermatophytic infections modified by the use of immunomodulators such as calcineurin inhibitors.1
Dermatophytes metabolize the dead keratin and evokes an inflammatory response, this response may be suppressed by the use of immunosuppressants such as corticosteroids. This results in a varied morphological presentation of the classical dermatophytic infections. Tinea incognito lesions have a less raised margin and usually scaling is absent or minimal. They present with extensive involvement, pruritis, erythematous papular or pustular lesions, mimicking other dermatological conditions.2
Dermatophytic infection being very common and very simple to diagnose is a diagnostic dilemma due to steroid abuse. Hence making a simple curable infection into a chronic persistent dermatological condition. As a treating doctor it’s important to recognize and educate the patients regarding the tinea infections and steroid abuse. This study is being done in our institution, SSIMS & RC, Davangere to study the various morphological presentations, epidemiology and etiological agent of tinea incognito.
Materials and Methods
With a level IV evidence, an observational study was performed from 2017 to 2019 in the department of Dermatology & Venerology, SS Institute of Medical Sciences and Research, Davangere, Karnataka, India. The cases for this study were recruited by convenient sampling technique. A group of about 100 patients with clinical features suggestive of tinea incognito belonging to both the sexes were included in the study after taking their consent.
In each case, the baseline data including age, gender, were collected and thorough general physical, local, and systemic examination were done with reference to clinical features of tinea incognito. Skin scrapings were collected from the lesion under aseptic precaution. All the scrapings were subjected to potassium hydroxide (KOH) preparation. The part of the sample was inoculated into Sabouraud’s Dextrose Agar (SDA) media for fungal culture. Later the fungus was identified by standard techniques.
A total of 100 patients with clinical features suggestive of tinea incognito were taken up for study and subjected for statistical analysis. The descriptive statistics were reported as mean (SD) for continuous variables, frequencies (percentage) for categorical variables. Data were evaluated with IBM SPSS Statistics for Windows, Version 24.0, IBM Corp, Chicago, IL.
Out of 100 patients in our study, 58% of population belong to 20 to 40 years of age. The mean age of study population was 32.83 years. The males (n=58, 58%) outnumbered females (n=42, 42%) in our study. According to modified Kuppuswamy scale, the middle class strata population were highest of upto 57% (n=57) followed by high class 43% (n=43).
Almost 29% cases remain asymptomatic followed by 34% itching and 37% burning sensation. Diabetes (20%) remain highest among the study population in co-morbid illness. The source of drug responsible for tinea incognito were highly suggested by friends (29%) followed by physician (14%) (as shown in Figure 5). The duration of steroid usage among the study population were mentioned in Figure 6 .
Out of the steroids and creams used in our study, the combination use of drugs account for 35% of population, clobetasole propionate in 31%, clobetasole propionate with salicylic acid in 19%, betamethasone valerate in 10% and mometasone in 5% of population. Among our study population, 77% cases showed erythema followed by 48% of hypopigmentation (as shown in Figure 7). The scraping of lesion showed positive KOH mount in 71% and negative KOH mount in 29%. The maximum cases shown growth of T.mentagrophytes (n=55, 46%) in SDA media is shown in Figure 8.
The term tinea incognito was originally described by Ive and Marks in the year 1968 for the atypical dermatophytic infections with prior use of topical or systemic corticosteroids.3 Tinea incognito (TI) is defined as tinea modified by the improper use of systemic or topical corticosteroids. As the use of topical corticosteroids has been increasing gradually in many dermatologic diseases, the number of cases of modified tinea has also increased.4, 5, 6 We propose that tinea incognito (certain dermatophytosis) have lost their clinical manifestation because of irrational use of systemic/topical corticosteroids.7 It is been suggested that the use of corticosteroids decreases the fungus-induced local inflammation, and this may allow the fungus to grow slowly with less erythema or scaling causing a “modification” of the typical manifestation of tinea.5, 6, 7
In our observational study done in the medical college setup, we encountered males (58%) outnumbered females (42%) with middle class strata (57%) being affected the most among study population. The presenting complaints were itching and burning sensation in the involved areas of the body. The co-morbid illness associated among our study population were diabetes being the highest followed by hypertension and IHD. Kim et al stated female preponderance with face as the most common site of predilection for TI presentation.8
The source of corticosteroids misuse among our study population were suggested by friends (29%), physicians (14%) and dermatologists (8%). Kim et al stated that dermatologists contributed 40% of TI. In our study, the combination use of drugs account for 35% of population followed by clobetasole propionate in 31% of study population.8 Ansar et al. found that 64.3% of their patients were treated at home by themselves, 21.4% by general physicians, and 14.3% by dermatologists.9 Mahar S et al. in India, found the most common reason for steroid abuse was fungal infections (38%). They also found that betamethasone valerate (72.8%) was the most commonly used topical corticosteroids.10
In our study, the clinical manifestation of erythema topped in 77% of population followed by hypopigmentation in 48% of study population. A few studies reported that the clinical features of TI were variable such as eczema‑like, psoriasis‑like and lupus erythematosus‑like lesions.9, 11, 12
The scarping of lesion under KOH mount revealed 71% positivity for dermatophytosis. Among all cases, Tinea mentagrophytes (46%) were grown in SDA agar culture followed by Tinea rubrum (32%). Various studies confirmed that Trichophyton rubrum was the most frequently identified dermatophyte among TI.13, 14, 15, 16, 17 Dutta B et al. in their prospective observational study of 100 patients conducted in India, found that Tricophyton (63%) was most common species isolated on culture. Tricophyton rubrum was the most common followed by Tricophyton mentagrophytes, other species like Tricophyton tonsurans, Epidermophyton floccosum and Microsporum canis were also isolated. This study also states that in majority of the cases pharmacists were responsible for prescribing medications.18
The steroid misuse is the major rising epidemic spread of superficial fungal infections across the country. More awareness regarding adverse effects of steroids in fungal infections is needed among doctors, paramedics and the general population. The production and marketing of irrational topical formulations containing a combination of steroid and antifungal needs to regulated. There is a need to educate community and medical professional that topical steroids are also dangerous, have serious side effects and judicious as well as rational use is anticipated to prevent tinea incognito.