Clinical features and nail clippings in 52 children with psoriasis.

Background/objectives: Nail clipping, the act of cutting the distal portion of a nail for microscopic analysis, can complement the diagnosis of skin diseases with nail involvement, such as psoriasis. This study aimed to describe histopathologic findings on 81 nails from 52 children and adolescents with skin psoriasis and to determine whether these changes correlated with the severity of skin and nail involvement.

Methods: Children with psoriasis were enrolled in this cross-sectional study to obtain Psoriasis Area and Severity Index (PASI) and Nail Psoriasis Severity Index (NAPSI) scores. The most altered nails were processed using periodic acid-Schiff with diastase staining.

Results: Fifty-two patients with a median age of 10.5 years were included. The median Nail Psoriasis Severity Index score of the 20 nails from these patients was 17 (range 3-80). The most common findings were pitting (94.2%), leukonychia (73.0%), and longitudinal ridges (63.5%). Eighty-one nail fragments were collected by clipping. Neutrophils were found in 6 samples (7.6%) and serous lakes in 15 (19%). Median nail plate thickness was 0.3 mm (range 0.1-0.63 mm). Patients whose nails had neutrophils had a higher median PASI score (6.1 vs 2.0, P = .03). Patients whose nails had serous lakes had higher median PASI (5.3 vs 1.9, P = .008) and NAPSI (median 45.0 vs 18.0, P = .006) scores.

Conclusion: There seems to be a correlation between some microscopic nail features in children with psoriasis and their PASI and NAPSI scores, so nail clippings from children with suspected psoriasis may help with diagnosis, especially in the presence of neutrophils, and in excluding onychomycosis.