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Species identification of dermatophytes in paraffin-embedded biopsies with a new polymerase chain reaction assay targeting the internal transcribed spacer 2 region and comparison with histopathological features.
- Source :
-
The British journal of dermatology [Br J Dermatol] 2016 Apr; Vol. 174 (4), pp. 869-77. Date of Electronic Publication: 2015 Dec 26. - Publication Year :
- 2016
-
Abstract
- Background: Dermatophytosis is a very common skin infection with a broad clinical spectrum. Biopsies are often used to confirm the diagnosis, especially when the clinical presentation is unusual. Not uncommonly, organisms are hard to find even with periodic acid-Schiff stains. Polymerase chain reaction (PCR) for dermatophytes can be used in such cases.<br />Objectives: To test a new PCR assay allowing species identification of dermatophytes on paraffin-embedded biopsies, and to reassess histopathological criteria for diagnosis of dermatophytosis.<br />Methods: In total, 121 biopsies of 92 patients with clinical suspicion of tinea were included. In 42 samples the clinical diagnosis had been confirmed histopathologically, and in 79 no fungal elements had been identified. PCRs targeting the internal transcribed spacer (ITS)2 region of dermatophytes were performed on the biopsies with subsequent sequencing. Sections were reassessed for the presence/absence of hyphae/spores, pattern and composition of infiltrate, and epidermal/follicular changes. Patient charts were reviewed for clinical data.<br />Results: The new ITS2 PCR assay detected 94% of the dermatophyte infections (compared with 79% identified by microscopy). Trichophyton rubrum was the dominant species (89%), and other species identified were Trichophyton verrucosum (2%), Microsporum canis (4%), Epidermophyton floccosum (2%) and Trichophyton interdigitale (4%). In particular, infections with T. interdigitale and manifestations with prominent spongiosis were not diagnosed histologically. Intracorneal neutrophils, which have been emphasized as a histopathological clue to dermatophytosis, were present in only 46% of PCR-positive samples.<br />Conclusions: Molecular species identification of dermatophytes via ITS2 PCR can easily be implemented in a routine dermatopathology setting. It is fast and highly specific and improves the sensitivity of histopathological diagnosis of dermatophytosis.<br /> (© 2015 British Association of Dermatologists.)
- Subjects :
- Adolescent
Adult
Aged
Aged, 80 and over
Biopsy
Child
DNA, Fungal analysis
DNA, Ribosomal Spacer isolation & purification
Dermatomycoses pathology
Female
Foot Dermatoses parasitology
Foot Dermatoses pathology
Hand Dermatoses parasitology
Hand Dermatoses pathology
Head
Humans
Male
Middle Aged
Polymerase Chain Reaction methods
Sequence Analysis, DNA
Skin parasitology
Torso
Young Adult
Arthrodermataceae isolation & purification
Dermatomycoses parasitology
Phylogeny
Skin pathology
Subjects
Details
- Language :
- English
- ISSN :
- 1365-2133
- Volume :
- 174
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The British journal of dermatology
- Publication Type :
- Academic Journal
- Accession number :
- 26556042
- Full Text :
- https://doi.org/10.1111/bjd.14281