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Caring for common nail disorders is an important skill for any general practitioner. In this review, we will discuss the most commonly encountered nail conditions that may come to you for consultation.

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Paronychia

Paronychia describes a painful condition where there is erythema and purulent drainage coming from an infected nail and surrounding skin. It is most commonly caused by an infection of streptococcus pyogenes or staphylococcus aureus. However, chronic or recurrent disease should raise suspicion for herpes simplex virus. The best way to diagnose paronychia is to culture the purulent drainage. The infection is treated by incision and drainage followed by systemic antibiotics or antivirals.

Onychomycosis

Onychomycosis is a fungal infection of the nail. Patients have nail thickening, discolouration, and subungual debris. It is incredibly common and often recurs despite therapy. The best way to confirm the diagnosis and differentiate this condition from psoriatic nails is to perform nail clipping. The nail specimens are sent to culture and histopathological staining for fungal elements.

Treatment of onychomycosis is challenging and can range from topical remedies, oral antifungals, to laser treatments. Topical options are often unsuccessful, and systemic therapy may pose risk to those with many underlying comorbid conditions. Laser treatment can be quite expensive and does not prevent a recurrence. Patients should be counselled that nails, especially toenails, may take up to 18 months to completely replace themselves. Thus, it may also be difficult to gauge treatment efficacy in a short period of time.

Digital mucous cyst

Patients with a skin-coloured, smooth round papule abutting a joint on the finger likely have a digital mucous cyst. These are very common and are thought to be outpouchings of the synovial lining. They can be painful due to the pressure of purulent buildup, thus incision and drainage may provide symptomatic relief. Unfortunately, these do recur, in which case definitive excision can be performed by a hand surgeon.

Longitudinal melanonychia

Longitudinal melanonychia describes a nail finding with vertical, pigmented lines that run down a nail. This finding gives a “striped” look to the nails. It can be due to a variety of causes, including certain medications, genetics, to infections. The most important cause of longitudinal melanonychia that we worry about is melanoma. A biopsy can be performed to evaluate for melanoma. Suspicion for melanoma is high if the melanonychia is progressive. Additionally, the Hutchinson sign, a sign that describes pigment extending beyond the nails and onto the proximal cuticle, is also highly suggestive of melanoma.

Nail findings and underlying systemic disorders

Brittle nails are a common complaint and may be due to chronic wet work, frequent use of nail polish, and malnutrition. Rarely, they may be a manifestation of an uncommon auto-inflammatory disease, such as lichen planus.

White nails are also referred to as leukonychia and may be caused by trauma to the nail. Patients may get white nails from manicures, rough handiwork, or even tight-fitted shoes. Rarely, diffuse whitening of the nails, especially in younger patients, can be a sign of genetic disorders. When suspected, it is recommended that these patients get referred to a pediatric specialist or geneticist.

Koilonychia, or spoon nails, are often a sign of iron deficiency in adults but can be a normal finding in children. These patients may benefit from a full workup for iron deficiency and should be treated with appropriate supplementation.

Psoriasis is a common skin condition that may also affect nails. Common findings include pitting, thickened nails, oil spots, and onycholysis. It may be difficult to differentiate a psoriatic nail from toenail fungus because fungus may also cause pitting, thickening, and onycholysis. A nail clipping sent for culture and histopathological staining as mentioned above.

In conclusion

As a GP, understanding the management and treatment of common nail disorders can be incredibly helpful in your practice. From common infections to signs of systemic disease, nails can be an important part of your physical exam that helps you optimise your patient’s care.

References

Ali Alikhan and Thomas L. H. Hocker. “ Review of Dermatology.” ELSEVIER 2017. p191-203

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