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CASE REPORT
Year : 2022 | Volume
: 26
| Issue : 3 | Page : 26-28
Tinea incognita with secondary bacterial infection
Daniel A Nadelman
Department of Dermatology, University of Michigan Medical School, Ann Arbor, MI, USA
Correspondence Address:
Mr. Daniel A Nadelman
University of Michigan Medical School, Ann Arbor, MI
USA
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/jdds.jdds_22_19
Tinea incognita is a phenomenon occurring when a fungal infection is erroneously treated with topical corticosteroids. This worsens the underlying infection without becoming clinically apparent until treatment is withdrawn, in which case the tinea infection becomes acutely symptomatic. We herein report a case of tinea incognita in a young woman treated with high-potency topical corticosteroids, leading to worsening dermatophyte infection and coinfection with Klebsiella oxytoca. The resulting infection required aggressive oral and topical antimicrobial treatment before resolving. This case illustrates the potentially harmful sequelae of using high-potency topical corticosteroids without first ruling out tinea infection.
Keywords: Bacterial coinfection, folliculitis, tinea incognita, topical corticosteroids
Tinea incognita results when a fungal infection of the skin is misdiagnosed as another dermatologic condition and is inappropriately treated with topical corticosteroids. This masks the clinical appearance of the infection, resulting in steady dermatophyte growth without overt clinical signs.[1] The infection continues to expand “incognita” (i.e. without making itself known) until the steroid treatment is stopped, at which point the severity of the tinea infection becomes clearly apparent.[2] In rare cases, severe tinea incognita leads to bacterial coinfection, which requires more extensive treatment.[1],[2] Here, we report a case of tinea incognita complicated by bacterial superinfection in a patient using high-potency topical corticosteroids.
Case ReportA 26-year-old Caucasian woman who had recently begun cosmetically waxing her axillae developed several painful erythematous papules in her right axilla. She was diagnosed with folliculitis and was treated with topical 1% clindamycin and 0.1% mometasone for 1 week. Her symptoms initially resolved, but several days after finishing her medication course, she developed diffuse burning, pruritus, and a faintly erythematous papular rash with minimal scale in her right axilla [Figure 1]. She was diagnosed with allergic contact dermatitis and was started on alclometasone 0.05% for 1 week. During this time, her symptoms improved, but immediately after completing treatment, her rash returned with worsening severity. She decided to self-medicate for 3 days with 0.05% clobetasol ointment (obtained from a friend), which again led to initial improvement. After stopping clobetasol, however, her condition acutely worsened. A large erythematous annular plaque with central clearing, peripheral erythema, and scaling developed [Figure 2]. A day later, the lesion began to crust and weep fluid, and the patient experienced subjective fever and chills. Potassium hydroxide (KOH) preparation was floridly positive with branching hyphae, and culture of the fluid grew Klebsiella oxytoca. The patient subsequently began a 7-day course of oral amoxicillin-clavulanate, topical clotrimazole 1% cream, and topical ketoconazole 2% cream. Her symptoms were markedly improved after 2 days [Figure 3], and several days after completing the antibiotic course and antifungal therapy, her rash was nearly completely resolved [Figure 4].
Figure 2: Erythematous annular plaque with central clearing and peripheral erythema with scale after topical corticosteroid treatment
Figure 3: Improvement of the rash after 2 days of antibiotic and antifungal treatment Discussion Tinea incognita incidence has been increasing in recent years as topical steroids have been made more readily available to patients.[1],[3] These topical agents are often used inappropriately in the setting of underlying fungal infection, resulting in tinea incognita. In this patient, initial treatment of folliculitis with clindamycin and mometasone likely predisposed her to developing a dermatophyte infection, and this risk was further increased when she began using alclometasone. Her tinea infection was further masked (i.e. made “incognita”) by the use of the high-potency topical clobetasol. This allowed for undetected expansion and growth of the infection, which was only clinically evident after the patient stopped all steroid uses [Figure 1] and [Figure 2]. The resulting florid fungal infection predisposed the patient to bacterial coinfection with K. oxytoca.
When compared with standard tinea infection, tinea incognita is less erythematous and scaly during the time that the patient is undergoing steroid treatment.[4] However, the infection often becomes more extensive once treatment is stopped and therefore can be more symptomatically distressing.[1],[4],[5] Tinea incognita infection most commonly occurs on the face or in areas of sweating and abrasion, such as the axillae.[6] It is most commonly associated with topical corticosteroid treatment (e.g., high-potency topical agents such as clobetasol) but may also occur with topical tacrolimus, systemic corticosteroids, and systemic immunosuppression.[1],[4],[7] The disease is also more likely to arise in patients with a generalized immunosuppressed status, such as those with human immunodeficiency virus.[6],[8] Patients with severe tinea incognita may develop bacterial superinfection, as occurred in this patient. This often requires systemic antibiotic treatment. In addition, the fungal infection may become so extensive that systemic antifungal treatment is required.[9] Majocchi's granuloma is more likely to develop in patients with tinea incognita; this also requires systemic antifungal therapy.[10]
Prevention of tinea incognita and its sequelae can be achieved by definitively ruling out tinea infection (e.g., by skin scraping and KOH preparation) prior to initiation of topical corticosteroids or immunosuppressive agents.[1],[4] It should be on the differential for patients treated with such agents who have not responded to therapy, and clinicians should be aware of this association prior to prescribing these medications.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References
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