Diagnosis and treatment monitoring of toenail onychomycosis by reflectance confocal microscopy: prospective cohort study in 58 patients.
BACKGROUND
The clinical presentation of onychomycosis is often nonspecific and can lead to inappropriate antifungal therapy. Available mycologic tests share many drawbacks.


OBJECTIVE
We sought to evaluate the accuracy of reflectance confocal microscopy (RCM) for the diagnosis of onychomycosis compared with standard mycologic tests.


METHODS
In all, 58 patients with suspected onychomycosis were enrolled prospectively. RCM, potassium hydroxide preparation, and fungal culture were performed at baseline and after treatment in patients with confirmed onychomycosis. RCM diagnosis of onychomycosis was based on the presence of filamentous and/or roundish structures in the nail plate, corresponding respectively to septate hyphae and/or arthroconidia.


RESULTS
Of patients, 46 of 58 were correctly classified by RCM, with a diagnosis yield of 79.3%, sensitivity of 52.9%, specificity of 90.2%, positive predictive value of 69.2%, and negative predictive value of 82.2%. The use of a handheld RCM imager permitted a faster examination with the same accuracy. RCM performed after treatment in 9 patients showed a normal nail plate, and healing was confirmed by mycologic tests or by follow-up.


CONCLUSIONS
Existing RCM scanner heads are not intended for nail examination.


CONCLUSIONS
RCM has excellent specificity and can be used as a rapid, office-based test to strengthen the prescription of antifungal therapy and for follow-up. Technical improvement could aid sensitivity.
Dermatology Department, Centre Hospitalier Universitaire de Nice, Nice, France.
Momen
M
Pharaon
Parasitology Mycology Laboratory, Centre Hospitalier Universitaire de Nice, Nice, France.
Martine
M
Gari-Toussaint
Dermatology Department, Centre Hospitalier Universitaire de Nice, Nice, France.
Abdallah
A
Khemis
Clinical Research Center (CRC), Centre Hospitalier Universitaire de Nice, Nice, France.
Kevin
K
Zorzi
Galderma Research and Development, Sophia Antipolis, France.
Laurent
L
Petit
Galderma Research and Development, Sophia Antipolis, France.
Philippe
P
Martel
Nail Disease Center, Cannes, France.
Robert
R
Baran
Nail Disease Center, Cannes, France.
Jean Paul
JP
Ortonne
Dermatology Department, Centre Hospitalier Universitaire de Nice, Nice, France; L'Institut National de la Santé et de la Recherche Médicale U 1065, Team 12, Nice, France.
Thierry
T
Passeron
Dermatology Department, Centre Hospitalier Universitaire de Nice, Nice, France.
Jean Philippe
JP
Lacour
Dermatology Department, Centre Hospitalier Universitaire de Nice, Nice, France; Clinical Research Center (CRC), Centre Hospitalier Universitaire de Nice, Nice, France; INSERM U 1065, Team 1, Nice, France; Groupe Imagerie Cutanée Non Invasive de la Société Française de Dermatologie. Electronic address: bahadoran.p@chu-nice.fr.
Philippe
P
Bahadoran
D000368:Aged; D005260:Female; D005533:Foot Dermatoses / Q000175:diagnosis* / Q000628:therapy*; D006801:Humans; D018613:Microscopy, Confocal / Q000379:methods*; D008875:Middle Aged; D014009:Onychomycosis / Q000175:diagnosis* / Q000628:therapy*; D011446:Prospective Studies; D012680:Sensitivity and Specificity
confocal; onychomycosis; reflectance confocal microscopy