Background: Of all nail disorders seen in dermatology offices, half of them are due to onychomycosis. The main differential diagnosis is nail psoriasis. The objective of this study was to compare the microscopic findings, other than the presence of fungi, in the clipping of onychomycosis versus normal nails and nail psoriasis.
Methods: Cross-sectional study of onychomycosis cases, analyzed by clipping and compared with data on normal nails and those with nail psoriasis.
Results: Sixty-two onychomycosis samples were compared with 30 normal nails and 50 nails with psoriasis. In onychomycosis, measurement of subungual region, serous lakes, neutrophils and number of layers of parakeratosis are more intense than in psoriasis. Onychocariosis is less common in psoriasis, while bacteria are more frequent. The nail transition zone is more commonly blurred and irregular in onychomycosis.
Conclusion: Clipping helps in the differential diagnosis of onychomycosis and nail psoriasis and may be useful even when fungi are not found.