Of all nail disorders seen in dermatology offices, half occur due to onychomycosis. The main differential diagnosis is nail psoriasis.

The purpose of a recent study published in Anais Brasileiros de Dermatologia was to compare the microscopic findings, other than the presence of fungi, in clippings of onychomycosis versus normal nails and nail psoriasis.

This was a cross-sectional study of onychomycosis cases – analyzed by clippings and compared with data on normal nails and those with nail psoriasis.

Here, 62 onychomycosis samples were compared with 30 normal nails and 50 nails with psoriasis. It was observed that 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. On the other hand, the nail transition zone is more commonly blurred and irregular in onychomycosis.

It was inferred that clippings help in the differential diagnosis of onychomycosis and nail psoriasis, and may be useful even when fungi are not found.

Source: Anais Brasileiros de Dermatologia. 2019 Jul 29;94(3):344-347. doi: 10.1590/abd1806-4841.20198301.