Chapter 14: Hair and Nails
Nails
In addition to disorders that primarily affect the nails, abnormalities in the nail may be markers of systemic conditions and overall health status. They can also provide useful clues towards certain skin conditions when the appearance of the rash is not diagnostic.
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Terminology for nail findings and their clinical significance:
| Description | Clinical Significance | |
| Onycholysis | Distal nail plate detaches from nail bed causing white appearance distally | Psoriasis and onychomycosis most common; trauma, drugs (commonly tetracyclines), tumors under nailbed |
| Beau’s lines | Transverse depressions of the nail plate | Most often trauma; eczema around nail; involvement of multiple digits at same level suggests systemic cause |
| Onychomadesis | Detachment of nail plate from proximal nail fold (a depressed groove replaces proximal nail plate) | Single nail – most often trauma Multiple – systemic cause such as HFMD |
| Trachyonychia | Diffuse homogenous roughness, loss of translucency | Isolated finding Alopecia areata, lichen planus, psoriasis, eczema |
| Pitting | Punctate depressions of nail plate surface | Psoriasis, alopecia areata, eczema |
| Splinter hemorrhages | Red to purple thin longitudinal lines in the nail plate | Trauma (most common), psoriasis, onychomycosis; proximal splinters are rare and suggest systemic disease (e.g. endocarditis, vasculitis) |
| Longitudinal melanonychia | Longitudinal brown to black band(s) | Multiple: physiologic, trauma, drugs, systemic cause Single: nevus, melanoma |
| Subungual hyperkeratosis | Thickened nail due to build-up of scale under the nail plate | Onychomycosis, psoriasis, eczema |
| Koilonychia | Spoon-shaped nails | Normal in 2nd-4th toes in children aged 1-4 years; Adults: severe iron deficiency |
