MALDI-TOF mass spectrometry proves effective for diagnosing onychomycosis in nail psoriasis

Xia & He Publishing Inc.Oct 26 2024

Background and objectives

Nail psoriasis is common in patients with plaque psoriasis and is associated with morbidity, including onychomycosis, which can complicate psoriasis treatments and be difficult to differentiate. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry is a fast and simple technique for identifying microorganisms through protein analysis. This study aimed to determine the sensitivity and specificity of MALDI-TOF for diagnosing onychomycosis in patients with nail psoriasis, by using conventional mycological and histological methods as the reference standard.

Methods

A prospective study was conducted on 88 patients with clinically and histopathologically confirmed nail psoriasis. One hundred nail samples were obtained for direct examination, fungal culture, and mass spectrometry. None of the patients were receiving antifungal or systemic immunosuppressive therapy at the time of sampling.

Results

Potassium hydroxide preparation and fungal culture were positive in 58 out of 100 nail samples from patients with psoriasis. MALDI-TOF identified onychomycosis in 68 out of 100 samples, distinguishing these cases from nail psoriasis without onychomycosis (32 out of 100). An excellent correlation (0.95) was found between MALDI-TOF and conventional onychomycosis diagnostic methods. The sensitivity and specificity of MALDI-TOF for diagnosing onychomycosis in patients with psoriatic nails were 95.4% and 97.5%, respectively.

Conclusions

MALDI-TOF can be used to accurately differentiate cases of nail psoriasis without infection from those with onychomycosis.