Expert Assessment for Nail Disorders and Nail Disease

This is the most common nail disorder, accounting for 50% of all nail-related consultations. It is a fungal infection of the nail unit, affecting both fingernails and toenails, with toenail involvement occurring far more frequently. The most frequent cause is Trichophyton rubrum (a type of dermatophytic fungus); there are other potential dermatophyte and non-dermatophyte infectious causes but these are much less prevalent. Specific fungal causes can be found in the source below.Source: Onychomycosis – StatPearls – NCBI Bookshelf (opens in a new tab)

Onychomycosis typically presents as a white or yellow-brown discolouration of the nail. There is often thickening of the nail plate (onychauxis) and detachment of the nail from the nail bed (onycholysis). Based on the pattern of invasion, onychomycosis can be divided into clinical subtypes; it is beyond the scope of this patient information context to discuss these individually, but more information can be found in the source below.Sources: Diseases mimicking onychomycosis – PubMed (opens in a new tab); Onychomycosis: Clinical overview and diagnosis – PubMed (opens in a new tab)

Diagnosis

The diagnosis of onychomycosis can be strongly suggested based on clinical features as described previously. Dermoscopy of the nail is helpful to differentiate it from other nail disorders. For atypical, treatment-initiating/resistant or clinically ambiguous onychomycosis, further diagnostic work-up may include nail clippings and/or scrapings sent for fungal microscopy and culture. Microscopy results with PAS staining are widely considered ‘gold standard’ and should be available within 1–2 days; culture results within 2–3 weeks can identify the specific type of fungus with a high specificity but have a low sensitivity, meaning false negatives with cultures alone are common.Sources: Dermoscopy as a first step in the diagnosis of onychomycosis – PubMed (opens in a new tab); Assessment | Diagnosis | Fungal nail infection | CKS | NICE (opens in a new tab)

Treatment

Onychomycosis is notoriously difficult to treat because of the deep-seated nature of the fungus within the nail plate, the prolonged treatment required for resolution, poor patient compliance and frequent recurrences. Microbiological confirmation is usually recommended prior to starting treatment, especially with oral antifungal medications, to ensure targeted therapy is used and to minimise exposure to potentially toxic antifungal medications. Treatment options include oral antifungal therapy, topical antifungal therapy, laser therapy and surgical avulsion.Source: Challenges and Opportunities in the Management of Onychomycosis – PubMed (opens in a new tab)

Oral antifungal treatment (terbinafine, itraconazole, fluconazole) is usually considered gold standard and often recommended as the first-line therapy when more than 50% of the nail is affected, multiple nails are affected or the nail matrix is affected. Oral treatment has a shorter course of action and higher cure rates when compared to topical treatments. However, topical treatment may be suggested in mild/moderate cases (less than 50% of the nail affected, without matrix involvement) of onychomycosis, due to the reduced risk of potential adverse effects when compared to oral treatments. Combination therapy can be used and has been shown to increase the cure rate.Sources: Onychomycosis: An Updated Review – PMC (opens in a new tab); Update: medical treatment of onychomycosis – PubMed (opens in a new tab)

Laser treatment is a safe, non-invasive, localised treatment option for onychomycosis. Most laser therapies use the principle of selective photothermolysis, whereby the laser energy is absorbed by the fungal cells, elevating the temperature and resulting in fungal cell death. It is a well-tolerated treatment modality but its efficacy when compared to antifungal therapies is less. Unfortunately, this is not something currently offered at Clinic 360.Source: Challenges and Opportunities in the Management of Onychomycosis – PubMed (opens in a new tab)

Psoriasis is a chronic inflammatory skin condition that can also affect the nails (please see our Psoriasis section). Nail psoriasis is a subtype of psoriasis and can manifest prior to any evidence of the cutaneous disease in up to 10% of cases. It is highly prevalent, affecting up to 80% of patients with plaque psoriasis and 97% of patients with psoriatic arthritis (joint involvement). It is associated with a significant disease burden and a negative impact on quality of life.Sources: Epidemiology of psoriasis in hard-to-treat body locations: data from the Danish skin cohort – PubMed (opens in a new tab); Nail Psoriasis: Diagnosis, Assessment, Treatment Options, and Unmet Clinical Needs – PubMed (opens in a new tab); Treatment of Nail Psoriasis – PubMed (opens in a new tab)

Nail psoriasis typically presents with key clinical features according to the structure that is involved within the nail unit. When psoriasis is present within the nail matrix, pitting (studded depressions), Beau lines (horizontal depressions or ridges in the nail plate) and crumbling of the nail plate are often seen. Psoriasis of the nail bed presents as oil-drop discolouration (translucent yellow-red discolouration in the nail bed), splinter haemorrhages (red linear streaks on the nail plate), subungual hyperkeratosis (thickening and scaling skin cells under the nail plate) and onycholysis (separation of the nail plate from the underlying nail bed).Source: Nail Psoriasis: A Review of Treatment Options – PMC (opens in a new tab)

Diagnosis

The diagnosis of nail psoriasis is made clinically with the aforementioned clinical signs. Investigations may be used in atypical presentations to exclude other potential causes. A nail biopsy of the nail matrix or nail bed may be used to identify the characteristic findings of psoriasis but is generally unnecessary.Source: Role of tangential biopsy in the diagnosis of nail psoriasis – PubMed (opens in a new tab)

Treatment

The treatment of nail psoriasis is often time-consuming and challenging, with an uncertain outcome and often with relapses. Treatment options can include topical or systemic therapy, which is based on the severity or extent of the disease. In mild disease, changes are limited to 1 or 2 nail beds with no functional impairment or systemic involvement, whereas moderate to severe disease is classified as changes beyond 2 nails with functional impairment and/or systemic involvement.Source: Nail Psoriasis: A Review of Treatment Options – PMC (opens in a new tab)

Topical treatments are often the first choice, but their effectiveness is limited to nail bed psoriasis; they are not very effective on nail matrix psoriasis because they do not penetrate the nail plate. Corticosteroids, both creams and intralesional applications, are effective in reducing inflammation, nail pitting, thickening and onycholysis. Other topical treatment options include vitamin D analogues such as calcipotriol, calcitriol and tacalcitol, which work by slowing the rapid growth of skin cells, reducing inflammation, thickening, pitting and discolouration. These therapies can be combined to enhance their effectiveness, improving penetration through the thick nail structure and tackling both the inflammatory and hyperproliferative aspects of the disease.Source: Optimal management of nail disease in patients with psoriasis – PMC (opens in a new tab)

Systemic therapies are recommended in patients with skin psoriasis or joint involvement, or in cases of moderate to severe nail psoriasis that have failed to respond to topical therapies. Treatment consists of the use of DMARDs (methotrexate, cyclosporine) that are effective in treating nail disease, and in refractory and severe cases the use of biologics can be considered but, due to potential side effects, is usually a last resort.Sources: Optimal management of nail disease in patients with psoriasis – PMC (opens in a new tab); Evaluation of the efficacy of methotrexate and cyclosporine therapies on psoriatic nails: a one-blind, randomised study – PubMed (opens in a new tab); Infliximab induction and maintenance therapy for moderate-to-severe psoriasis: a phase III, multicentre, double-blind trial – PubMed (opens in a new tab)

Paronychia is primarily an infection of the proximal and lateral fingernail and toenail folds, including the tissue that borders the root and side of the nail. There are both acute (less than 6 weeks) and chronic (more than 6 weeks) presentations, with infectious and non-infectious causes. Bacterial infection (Staphylococcus aureus) makes up the majority of cases, especially acutely. It is more commonly seen in women than in men, with a 3 to 1 ratio respectively. Risk factors include frequent, prolonged exposure of the hands to water or irritants, trauma to the nail fold, and underlying conditions such as diabetes and immunosuppression.Sources: Acute and Chronic Paronychia Revisited: A Narrative Review – PMC (opens in a new tab); Acute and Chronic Paronychia | AAFP (opens in a new tab)

Patients with acute paronychia present with a 2–5-day history of erythema, oedema, pain and marked tenderness in a single digit along the lateral proximal nail fold, often with evidence of purulent discharge.Source: Paronychia – StatPearls – NCBI Bookshelf (opens in a new tab)

Patients with chronic paronychia present with erythema, pain and swelling around the nail fold of greater than a 6-week duration. Symptoms are not as severe as with acute paronychia, hence patients often present later. It generally involves more than one digit; where a single digit is involved, other potential causes including malignancy should be excluded. It is commonly caused by mechanical or chemical irritants, though infection (usually fungal/candida) can still be attributed to chronic cases.Sources: Acute and Chronic Paronychia | AAFP (opens in a new tab); Paronychia – StatPearls – NCBI Bookshelf (opens in a new tab)

Diagnosis

The diagnosis is typically made on clinical grounds by examination of the hands along with the patient’s history. Investigations are usually reserved for atypical presentations or severe symptoms and may include imaging (in the case of severe infections where abscess formation is considered, osteomyelitis, or malignancy) and cultures (used in severe or refractory infections to target treatment).Source: Microbiological analysis of acute infections of the nail fold on the basis of bait thread test – PMC (opens in a new tab)

Treatment

The treatment of paronychia is specific to the underlying cause. For acute paronychia, treatment is determined by the degree of inflammation. In mild cases, warm soaks and topical antibiotic creams (mupirocin, gentamicin, bacitracin, neomycin) alone or in combination with a topical corticosteroid (betamethasone) are often effective for the treatment of uncomplicated bacterial paronychia. For persisting cases, oral antistaphylococcal antibiotic therapy should be started. Where abscess formation has developed, this should be surgically managed to allow for drainage.Sources: Acute paronychia: comparative treatment with topical antibiotic alone or in combination with corticosteroid – PubMed (opens in a new tab); Scenario: Management | Management | Paronychia – acute | CKS | NICE (opens in a new tab)

The treatment of chronic paronychia includes avoiding exposure to contact irritants, impeding inflammation and allowing the cuticle to heal through preventative measures (see the table in the source below), medical management and/or surgical intervention. The use of corticosteroids is considered the mainstay of therapy and is considered superior to topical antibiotics and systemic antifungals, with their use generally reserved for cases of fungal (candida) infection. Surgical management is typically reserved for patients with a well-formed abscess and/or failure to respond to medical intervention of at least a 6-month duration.Sources: Table – PMC (opens in a new tab); Acute and chronic paronychia of the hand – PubMed (opens in a new tab); Acute and Chronic Paronychia Revisited: A Narrative Review – PMC (opens in a new tab)

Melanonychia is a common cause of nail discolouration, accounting for nearly half of all cases seen in a dermatology clinic. Longitudinal melanonychia is the most common pattern, with a brown or black discolouration extending from the nail matrix to the free edge. Transversal or total melanonychia are rarely encountered. This discolouration is due to increased melanin production, with two potential mechanisms.Sources: Distinct Patterns and Aetiology of Chromonychia – PubMed (opens in a new tab); Melanonychia – Clues for a Correct Diagnosis – PMC (opens in a new tab)

• Melanocytic Activation: Increased melanin production from a normal number of activated melanocytes (cells of the skin responsible for skin colour) in the nail matrix. There are a number of potential underlying causes, including physiological (more commonly seen in individuals with black skin, Asians and Hispanics), trauma, infections, pregnancy, inflammatory skin disorders (psoriasis), systemic causes (Addison disease, Cushing disease), iatrogenic causes (medication, X-ray exposure), nutritional deficiencies and tumours.Source: Melanocytic Lesions of the Nail Unit – PMC (opens in a new tab)
• Melanocyte Proliferation: Increased melanin production secondary to an increased number of melanocytes in the nail matrix. There are three types of longitudinal melanonychia in this category: benign melanocytic hyperplasia within the nail matrix (nail matrix naevi/moles or nail matrix lentigo/freckle) and melanoma. The former two conditions are benign and are more commonly seen in children and adults, respectively, while the latter condition is malignant.Source: Melanocytic Lesions of the Nail Unit – PMC (opens in a new tab)

The vast majority of longitudinal melanonychia are caused by benign conditions; however, malignancy due to subungual melanoma or squamous cell carcinomas are also possibilities that must be excluded, due to the poor prognosis with delayed diagnosis.Source: Melanonychia – PMC (opens in a new tab)

Diagnosis

The underlying cause (benign/malignant) is often diagnosed through a combination of clinical features (the ABCDEF mnemonic helps identify risk factors for malignancy and can be accessed in the source below), dermoscopy and biopsy. As the clinical diagnosis of melanonychia is frequently difficult on clinical and dermoscopy assessment alone, biopsy is the gold standard and often necessary to make a definitive diagnosis.Sources: Melanonychia – PMC (opens in a new tab); Longitudinal Melanonychia: How to Distinguish a Malignant Condition from a Benign One – ScienceDirect (opens in a new tab)

Treatment

The treatment of melanonychia is specific to the underlying cause. Benign causes (race, ethnicity, harmless moles) do not necessitate treatment, though monitoring for changes in their appearance is recommended. Patients should be counselled for self-examination and to report any morphological changes. In the case of underlying infections, these are most commonly treated with antifungal medications; for iatrogenic causes, changes in medication may be made where possible, and addressing underlying medical conditions (systemic disease) and any nutritional deficiencies may cause regression of pigmentation. In cases of malignancy, most commonly due to subungual melanoma, these are often managed surgically with wide local excision or digit amputation depending on the grade and depth of the lesion, with or without sentinel lymph node mapping/biopsy.Sources: The ABC rule for clinical detection of subungual melanoma – PubMed (opens in a new tab); Melanonychia: Etiology, Diagnosis, and Treatment – PMC (opens in a new tab); The Prognosis of Nail Apparatus Melanoma: 20 Years of Experience from a Single Institute – PubMed (opens in a new tab)

Nail plate brittleness or splitting is a common complaint seen in dermatology clinics, affecting up to 20% of the population, especially women over the age of 50, with nail splitting being more prevalent in the hands than in the feet.Source: Incidence of brittle nails – PubMed (opens in a new tab)

Brittle nails manifest either through factors that alter nail plate production and/or factors that damage the nail plate itself. The condition is characterised by nails that flake, crumble, peel or break easily. The main clinical features are onychoschizia (horizontal, lamellar splitting of the free nail edge), onychorrhexis (longitudinal ridging, splitting or brittleness of the free nail edge) and keratin granulation, due to an accumulation and clumping of keratin on the nail plates (superficial, small white/yellow patches and striations).Source: Pathogenesis, Clinical Signs and Treatment Recommendations in Brittle Nails: A Review – PMC (opens in a new tab)

The condition is not always painful, but pain can occur from deep splitting or if any object were to catch the nail plate itself. They can cause significant cosmetic or functional impairments for patients, with even associated effects on mental health.Source: Perception of brittle nails in dermatologic patients: a cross-sectional study – PubMed (opens in a new tab)

Brittle nails have two forms and can have either ‘idiopathic courses’ or ‘secondary courses’ due to an array of different medical conditions.

• Idiopathic: In the absence of a definable medical reason. This is by far the most common subtype and is attributed to postmenopausal women and increasing age, and is almost exclusively seen in the fingernails. A possible explanation is linked to dehydration and reduced lipid production as we age, both considered important for normal nail plate synthesis.Source: Age-associated changes in integral cholesterol and cholesterol sulfate concentrations in human scalp hair and finger nail clippings – PubMed (opens in a new tab)

Secondary brittleness refers to the presence of an underlying medical condition that can be attributed to the nail disease. This includes:

• Inflammatory nail disorders such as psoriasis, with up to 50% of these patients having brittle nails. Other causes include eczema, lichen planus and alopecia areata.Source: Nail involvement as a negative prognostic factor in biological therapy for psoriasis: a retrospective study – PubMed (opens in a new tab)
• Infection: Superficial white onychomycosis is a cause of nail brittleness, due to damage of the nail plate secondary to keratin digestion by the fungi.Source: Nail digital dermoscopy (onychoscopy) in the diagnosis of onychomycosis – PubMed (opens in a new tab)
• Systemic Diseases and Medications: Patients with endocrine disorders (hypothyroidism) commonly have concurrent brittle nails, as do patients with impaired peripheral circulation (diabetes, arteriosclerosis, chronic anaemia and neurological conditions). Certain systemic medications used for treating cancers or chronic infections can be attributed to the disease, as can severe vitamin deficiencies (biotin, iron, vitamin C and vitamin D) crucial for keratin production.Sources: Brittle Nails and Hair Loss in Hypothyroidism – PubMed (opens in a new tab); Exposome Impact on Nail Health – PMC (opens in a new tab); Modulation of linear nail growth to treat diseases of the nail – PubMed (opens in a new tab)
• Trauma and Alteration of Nail Hydration: Trauma to the nail plate can be caused by mechanical forces; these include onychotillomania and onychophagia (nail biting) or exposure to solvents/solutions that affect the normal keratin homeostasis of the nail plate. Manicures that affect nail hydration are also a subsequent cause.Source: Exposome Impact on Nail Health – PMC (opens in a new tab)

Treatment

The majority of patients presenting to the dermatology clinic with brittle nails have an idiopathic cause. Treatment for these patients consists of supplementation with biotin (vitamin B7) and amino acids (especially cysteine) and the use of daily nail moisturisers (petrolatum jelly and lanolin) to lock in moisture and improve nail hydration. Patients should also be advised, where possible, to avoid repeated immersion in water and the use of detergents and soaps.Sources: The Role of Vitamins and Minerals in Hair Loss: A Review – PubMed (opens in a new tab); Pathogenesis, Clinical Signs and Treatment Recommendations in Brittle Nails: A Review – PMC (opens in a new tab); Wet working conditions increase brittleness of nails, but do not cause it – PubMed (opens in a new tab)

Secondary nail brittleness should be treated, where possible, by addressing the underlying cause along with local treatment. Local treatment is as discussed previously. The treatment of underlying causes may include the treatment/management of dermatological/systemic conditions, treating underlying infectious causes and stopping/changing medications where possible.Source: Pathogenesis, Clinical Signs and Treatment Recommendations in Brittle Nails: A Review – PMC (opens in a new tab)