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Bullous Tinea Pedis

      A woman in her 70s presented with a skin eruption on the left dorsal foot that had developed spontaneously 2 weeks before. The rash initially appeared with pruritic papules that evolved to fluid-filled blisters and persisted despite self-treatment with topical hydrocortisone 1% cream and antibiotic ointment. Examination revealed an erythematous plaque with tense and denuded bullae (Figure 1). She received oral cephalexin for presumed bullous impetigo. Bacterial culture and herpes simplex virus and varicella zoster virus polymerase chain reaction (PCR) swab results were negative. Over the ensuing 6 weeks, she continued to experience new bullae. She presented to the dermatology clinic, where examination showed an expanding annular plaque with peripheral scale (Figure 2).
      Figure thumbnail gr1
      Figure 1An erythematous plaque on the left dorsal foot involving the second and third digits proximally, with bullae formation and erosions from denuded blisters at initial presentation.
      Figure thumbnail gr2
      Figure 2An expanding annular erythematous plaque with peripheral scale, occasional vesicles, and maceration of the webspaces on the left dorsal foot, 6 weeks after the image in .
      Thirty percent potassium hydroxide (KOH) preparation demonstrated hyphae, confirming bullous tinea pedis. Fungal culture grew Trichophyton rubrum. The patient responded well to terbinafine cream and dilute acetic acid soaks.
      Bullous tinea, seen in adults and children, and most often affecting the feet, presents with an erythematous scaly rash with serous fluid-filled bullae, as opposed to the pus-filled blisters of bullous impetigo.
      • Maroon M.S.
      • Miller 3rd, O.F.
      Trichophyton rubrum bullous tinea pedis in a child.
      • Meykadeh N.
      • Waltermann K.
      • Schaller M.
      • Marsch W.C.
      • Fischer M.
      Bullous ulcerating tinea.
      • Shen W.C.
      • Chang Liao N.F.
      • Wu P.Y.
      Image gallery: widespread erosive tinea corporis mimicking autoimmune bullous dermatoses in a patient with lung cancer.
      Misdiagnosis and treatment delays are common.
      • El-Segini Y.
      • Schill W.B.
      • Weyers W.
      Case report: bullous tinea pedis in an elderly man.
      Differential diagnoses include bullous impetigo, bullous allergic contact dermatitis, thermal injury, edema-related bullae, or localized bullous pemphigoid.
      • Montagnon C.M.
      • Tolkachjov S.N.
      • Murrell D.F.
      • Camilleri M.J.
      • Lehman J.S.
      Subepithelial autoimmune blistering dermatoses: clinical features and diagnosis.
      Clues to diagnosis include unilateral, localized distribution; expanding annular scaling; concomitant onychomycosis; and a lack of response to topical corticosteroids. Thorough history, examination, and KOH preparation aid diagnosis. Topical terbinafine is effective against most culprit dermatophytes. Bullous tinea should be considered in the differential diagnosis of unilateral blistering dermatoses, especially when on the foot, to hasten diagnosis and effective treatment.

      Potential Competing Interests

      The authors report no competing interests.

      References

        • Maroon M.S.
        • Miller 3rd, O.F.
        Trichophyton rubrum bullous tinea pedis in a child.
        Arch Dermatol. 1989; 125: 1716https://doi.org/10.1001/archderm.1989.01670240118033
        • Meykadeh N.
        • Waltermann K.
        • Schaller M.
        • Marsch W.C.
        • Fischer M.
        Bullous ulcerating tinea.
        J Eur Acad Dermatol Venereol. 2009; 23: 846-847
        • Shen W.C.
        • Chang Liao N.F.
        • Wu P.Y.
        Image gallery: widespread erosive tinea corporis mimicking autoimmune bullous dermatoses in a patient with lung cancer.
        Br J Dermatol. 2020; 182: e54https://doi.org/10.1111/bjd.18520
        • El-Segini Y.
        • Schill W.B.
        • Weyers W.
        Case report: bullous tinea pedis in an elderly man.
        Mycoses. 2002; 45: 428-430https://doi.org/10.1046/j.1439-0507.2002.00767.x
        • Montagnon C.M.
        • Tolkachjov S.N.
        • Murrell D.F.
        • Camilleri M.J.
        • Lehman J.S.
        Subepithelial autoimmune blistering dermatoses: clinical features and diagnosis.
        J Am Acad Dermatol. 2021; 85: 1-14https://doi.org/10.1016/j.jaad.2020.11.076