Nail abnormalities occur in all age groups but are more prevalent in older adults. Nail disorders account for 10% of dermatologic disorders. Nail abnormalities can be categorized as surface texture irregularities, color changes, defects of nail plate attachment/nail shedding, tumors, or a combination of these. Brittle nails affect up to 20% of the population but are most prominent in older women and on fingernails. Different patterns of brittle nails can be seen in the same patient or can coexist in the same nail. Beau lines are transverse grooves caused by decreased keratinocyte activity in the proximal nail matrix. Nail pitting is due to abnormal keratinization in the proximal nail matrix. More than one-half of patients with psoriasis will have some nail involvement, and pitted nails are just one manifestation of nail psoriasis. Color changes may appear in the nail plate, nail bed, or nail matrix. In the nail unit, melanocytes are located only in the nail matrix. Brown-black nail changes are known as melanonychia and are caused by melanocyte activation or proliferation. Melanoma typically presents as longitudinal brown-black nail lines, but in approximately 30% of cases, it may present as a nail mass. Abnormal growth in the nail unit should raise concern for benign or malignant tumors, including the most common malignant tumor, squamous cell carcinoma. Nail clippings, ultrasonography, dermoscopy, and biopsy are useful for the diagnosis of nail abnormalities. Dermoscopy can assist in triaging lesions and differentiating those that can be safely observed from those that should be biopsied.
Nail abnormalities occur in all age groups but are more prevalent in older adults. The aging process, cumulative ultraviolet radiation exposure, trauma, infections, local nail unit diseases, systemic diseases, nutritional deficiencies, and medications can cause nail abnormalities.1,2 Nail disorders account for 10% of dermatologic conditions.3 Nail changes are generally not unique to a single condition, and similar findings can be seen in several conditions (Table 14,5).
SORT: KEY RECOMMENDATIONS FOR PRACTICE
| Clinical recommendation | Evidence rating | Comments |
|---|---|---|
| Treatment of isolated nail psoriasis includes steroid injections into the nail folds, topical steroids, or vitamin D analogues, either alone or combined. Systemic therapy should be used if there is concomitant systemic psoriasis.20 | C | Expert opinion and consensus guideline in the absence of clinical trials |
| Brown-black nail lines greater than 6 mm wide; lines that are darkening, widening, or bleeding; and lines that involve the nail folds (ie, Hutchinson sign) are concerning for subungual melanoma and require further investigation, generally with biopsy.27 | B | Consistent results from cohort studies and case series |
| When inflammatory disorders of the nail plate are suspected, such as nail psoriasis or infection, send nail clippings for evaluation.38 | C | Expert opinion and consensus guideline in the absence of clinical trials |
A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evidence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to https://www.aafp.org/afpsort.
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