What it is
The nails reflect a long list of skin and general conditions — fungal infection, psoriasis, lichen planus, inflammation of the skin around the nail, and mechanical damage from extensions, filing and the wrong way of cutting. The visit starts by establishing which of these it is, using dermoscopy of the nail and a clipping sent for microscopy and culture, because a great deal of what is called "fungus" turns out to be something else and is then treated for months with the wrong tablet. A pigmented band running lengthways along a nail is assessed separately and carefully, because it is occasionally the first sign of something that needs a biopsy.
What this page covers
- Nail sampling before treatment: clipping, KOH microscopy, culture and onychoscopy
- Onychomycosis, confirmed in the laboratory before any oral course, with liver function and drug-interaction review
- Nail psoriasis: pitting, oil-drop change, onycholysis and subungual thickening
- Nail lichen planus, which needs early treatment because matrix scarring does not reverse
- Acute and chronic paronychia, including the cuticle-pushing, nail-biting and unprotected-detergent causes of the chronic form
- Ingrown toenail: local care, partial nail avulsion, and phenol matricectomy for the recurrent case
- Brittle nails, assessed alongside iron and thyroid rather than treated with high-dose biotin
- Habit-tic deformity, which is diagnosed clinically and routinely mistreated as fungus
- Gel, acrylic and polygel damage, and true (meth)acrylate contact allergy — which also presents as facial and eyelid dermatitis by transfer
- Longitudinal melanonychia: dermoscopy, photographic documentation and the biopsy threshold
- Acral and nail melanoma recognition in skin of color, including Hutchinson sign
- Nail unit biopsy and nail surgery, with the possible lasting nail-plate change stated in the consent conversation
- Foot assessment and earlier referral in diabetes and poor circulation, where any nail wound complicates
Honestly
Nails grow slowly, so improvement follows that pace and a nail may not go back to the shape it had before. Not every thickened yellow nail is fungal, and a single dark band that is widening, darkening, has uneven lines, or is spreading onto the skin around the nail is a biopsy question rather than a cosmetic one — it should not be covered with polish or an extension before it is assessed, and nail melanoma is diagnosed late in exactly this skin.