Tinea pseudomibricata due to Trichophyton mentagrophytes: a rare case report.
Tinea pseudoimbricata is characterized by concentric scaly rings simulating tinea imbricata but caused by dermatophytes other than Trichophyton concentricum. We report a unique case of tinea pseudomibricata, its pathogenesis and review of previously reported cases. A 1.5-year-old baby developed concentric rings of scaly lesions over groins and buttocks following use of topical corticosteroids for 1 month. Mycological studies were performed to establish the diagnosis. Diagnosis of tinea pseudoimbricata was made on the basis of morphology of lesions and was confirmed by isolation of T. mentagrophytes on culture. Complete clinical and mycological cure was obtained with topical 1% sertaconazole given for 4weeks.
Key words: Tinea imbricata, tinea pseudoimbricata, Trichophyton mentagrophytes.
Tinea imbricata is an anthropophilic dermatophytosis caused exclusively by Trichophyton concentricum that is primarily seen in individuals of pure race residing in primitive isolated conditions and often is associated with poor hygiene.1 The exact mode of inheritance is unknown. It may have autosomal inheritance with incomplete penetrance/ autosomal recessive inheritance. Apart from genetic predisposition other factors implicated in causation include poor hygiene, impaired delayed type hypersensitivity reaction to T. concentricum antigen and T- lymphocyte hyporeactivity that leads to repeated waves of scaling in tinea imbricata.2
Tinea pseudoimbricata is an unsual form of tinea corporis/ tinea cruris masquerading as tinea imbricata irrespective of the etiological agent.
A 1.5-year-old baby was brought with annular erythematous plaques over the groins and buttocks since 3 months. Family history was negative for dermatophytosis. No evidence of protein energy malnutrition was present. History of application of topical corticosteroids was present since 1 month. On examination multiple, erythematous, concentric and circumscribed scaly patches were seen over the groins and gluteal folds (Figure 1). Differential diagnosis included tinea cruris and erythema annulare centrifugum. Provisional diagnosis of tinea imbricata was made on the basis of typical morphology of lesions. KOH mount of the scrapings taken from the margins of all the concentric rings revealed hyaline, septate, branching hyphae with several anthroconidia (Figure 2). Culture on Sabouraud's dextrose agar demonstrated creamish white colony with granular suface and raised centre; reverse showed yellowish brown pigmentation consistent with Trichophyton mentagrophytes (Figure 2).
Trichophyton test could not be done. Patient was treated with 1% sertaconazole cream for 4 weeks with complete resolution of lesions.
The term imbricata' is derived from the latin imbrex' and refers to the similarity to overlapping roof tiles. The unusual clinical picture seen in our patient is reminiscent of the rash described in tinea imbricata due to Trichophyton concentricum
Normally in response to dermatophytoses, the stratum corneum undergoes renewal process done by keratinocytes that leads to epithelial shedding, and consequently possible removal of the fungus.3 Also cell-mediated immune response is responsible for the control of infection.
In tinea pseudoimbricata impaired cell- mediated immune response due to application of topical corticosteroids would have resulted in persistence of fungi and formation of concentric rings. Also adhesion of T. mentagrophytes anthroconidia to the stratum corneum surface results in the formation of elongated fibrillary structures that appear to anchor and connect the anthroconidia to the tissue surface. This may prevent its removal from the host tissue.4
First reported case of tinea pseudoimbricata dates back to 1987, where Microsporum ferrugineum was the culprit fungi.5 Pei-Lun Sun described similar presentation with M. gypseum. None of them described associated immunodeficiency.6
Narang et al.7 reported a case of tinea capitis with concentric rings in an HIV-reactive patient due to T. tonsurans. Concentric rings were present over the entire scalp and forehead with diffuse thinning of hairs. Patients CD 43 count was 99 cells/mm . Complete clinical and microbiological cure was observed with oral terbinafine given for 3 weeks.
Lim and Smith8 described extensive tinea corporis resembeling tinea imbricata in a renal transplant recipient on immunosuppressive therapy. In this case, too, T. tonsurans was the culprit agent. Patient was maintained on tacrolimus and azathioprine. The similarity in clinical presentation was attributed to immunosuppresive processes utilized in preventing renal transplant rejection and that seen in immune response of patients with tinea imbricata.8
Batta et al.9 reported two patients of tinea corporis due to T. tonsurans and T. mentagrophytes. Cause of immunosupression was due to use of cyclical therapy with topical corticosteroids and topical antifungals because of indecision about the etiology of rash and its treatment.
A case report by Horque and Horden10 described concerntric rings in a 44 years old Afro-Carribean woman. Her annular erythema was diagnosed as that of lupus eyrthematosus and was treated with oral and topical corticosteroids and hydroxychloroquine but the rash continued to worsen. On repeating skin scrapings for culture T. tonsurans growth was obtained and rash cleared completely with oral terbinafine for 4 weeks.
A recent case report by Rao and Datta11 described similar presentation due to T. mentagrophytes and T. tonsurans. Cause of immuosupression in one of the cases was protein-energy malnutrition.
Thus on reviewing the literature it can be concluded that irrespective of immunological status, etiological agent and age, tinea corporis/ tine cruris can morphologically resemble tinea imbricata.
Though immunosupression has been postulated as a cause, more research about different aspects of dermatophytoses such as physiology, genetics, biochemistry and immunology is required to elucidate the cause in immunocompetent individuals.
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9. Batta K, Ramlogan D, Smith AG et al. Tinea indecisiva may mimic the concentric rings of tinea imbricata. Br J Dermatol. 2002;147:384.
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11. Rao AG, Datta N. Tinea corporis due to Trichophyton mentagrophytes and Trichophyton tonsurans mimicking tinea imbricate. Indian J Dermatol Venereol Leprol. 2013;79:554.
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|Publication:||Journal of Pakistan Association of Dermatologists|
|Date:||Jun 30, 2015|
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