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Intraepidermal neutrophils--a clue to dermatophytosis?
Simin Meymandi1, Shane G Silver, Richard I Crawford
1Division of Dermatology, University of British Columbia, Vancouver, Canada.
Background:
Dermatophyte infections are occasionally diagnosed by histopathology. Spongiotic or psoriasiform features are typical but non-specific, and neutrophils may be present within the stratum corneum. Traditionally, this latter finding has been felt to be a diagnostic clue for dermatophytosis, and usually precipitates a periodic acid Schiff (PAS-D) stain to confirm the presence of hyphae in the stratum corneum. Our objective was to evaluate whether the presence of neutrophils within the stratum corneum is a sensitive or specific test for dermatophytosis.
Methods:
We performed a retrospective case-control study on 303 cases of spongiotic or psoriasiform dermatitides over a 35-month period. Hematoxylin and eosin (H&E) and PAS-D stains were utilized to identify intraepidermal neutrophils and fungi.
Results:
The sensitivity and specificity for diagnosing dermatophyte infection based upon neutrophils within the stratum corneum were 62 and 59%, respectively. The positive and negative predictive values in our population were 4 and 98%, respectively.
Conclusion:
The histologic feature of neutrophils within the stratum corneum is neither sensitive nor specific in the diagnosis of dermatophytosis.