Nails not only have their own problems but also may be affected by many systemic diseases. They provide some guide to the likely cause. If the abnormality is widespread and symmetrical, it is more likely to have an endogenous than an exogenous explanation.
Nails Changes Associated with Systemic Disorders
Abnormally thinned, depressed in the center with raised edges giving an appearance of a Spoon, so-called spoon-shaped nails. It is seen in association with iron deficiency Anemia, Hypothyroidism, 50% of patients with idiopathic Hemochromatosis or following trauma, such as in garage mechanics who regularly fit tires. In Anaemia, nails revert to normal if anemia is corrected. It can be congenital (from birth).
Beau’s lines are transverse linear depressions in nail plates that occur simultaneously in all nails. They typically follow a systemic illness, zinc deficiency, malnutrition, uncontrolled diabetes mellitus, peripheral vascular diseases, syphilis, due to some drugs, or trauma because of the temporary arrest of the growth of nails. They subsequently migrate out as the nail grows. As with the Mees’lines timing of illness may be estimated by measuring the distance from the line to the proximal nail fold. (Nails grow approximately 1mm every 6-10 days)
Finger clubbing or Hippocratic nails (parrot- beak appearance ) is a distinct feature associated with a number of diseases. In the early stages, the normal angle between the nail plate and the proximal nail fold is lost followed by the drumstick’s appearance on fingernails and toes. The angle between the nail plate and proximal nail fold can increase by more than 180 degrees. The process usually takes years. Can be familial or idiopathic or show disorders of the pulmonary, cardiovascular system, and gastrointestinal systems such as bronchial carcinoma, Asbestosis (especially with mesothelioma), suppuration or fibrotic lung diseases, cyanotic heart diseases, infective endocarditis, inflammatory bowel diseases, biliary cirrhosis, and thyrotoxicosis. Vascular endothelial growth factors play a central role in the development of clubbing. It is a platelet derive factor induced by hypoxia and is produced by diverse malignancies.
Brown black pigmentation of the nails is termed melanonychia. It may be partial or total, transverse or linear, and may affect one or multiple nails. Brown nail bands are found normally in 90% of black people. Melanonychia is due to melanin, as in nevi, lentigos, and melanoma. Although there are many benign causes of longitudinal melanonychia, the most important cause is Subungual Melanoma. Benign melanonychia can be caused by drugs (such as zidovudine) or by vitamin B12 deficiency and Laugier-Huntziger syndrome in which there are pigmented bands in nails and pigmented macules on lips and oral mucosa.
Mees’ lines (also known as Aldrich or Reynolds’ lines) are transverse white bands 1-2 mm thick on the nail plate laid down during periods of stress. Usually one band per nail. Common associations are poisoning (Arsenic, Thallium, Fluorosis, carbon monoxide poisoning), severe infection, renal disease, cardiac failure, and malignant disease due to some chemotherapeutic agent. It is noted to occur at the same level in one or several nails. They move distally as the nail grows out.
Muehrcke’s lines are a strong indicator of hypoalbuminemia. These are stationary paired transverse bands that can result from a variety of different causes.
The lines are actually in the vascular bed underneath the nail plate. They do not move with nail growth and disappear when pressure is applied to the nail. This distinguishes them from “true leukonychia striata”. As in Terry’s and half-and-half nails, the pattern is thought to be formed by bands of localized edema exerting pressure on the surrounding capillaries.
Small longitudinal thin dark red-brown lines in nails that resemble splinters under the nail plate. Usually caused by trauma but can be related to systemic illnesses or drugs. Psoriasis and other medical and vascular events have been associated with splinter hemorrhages. If the lesion occurs distally on a single nail, it is less likely to be related to a systemic cause.
Yellow Nails Syndrome
Diffuse yellow, slow growing, thickened nail plates with absent lunula and cuticle. The surface remains smooth or acquires transverse ridges, indicating variation in growth rate. partial or total separation of the nail may occur. Most commonly associated with pulmonary problems such as pleural effusion, bronchiectasis, or chronic sinus infections. yellowish nail pigmentation has been reported in patients with AIDS. The underlying pathological process is thought to be related to impaired lymphatic drainage. The nail may spontaneously improve, even when the associated disease does not improve.
The proximal nail plate is white or light pink ground-glass looking (greater than 80% of the entire nail plate) with a 0.5-3 mm normal pink or brown distal band. The lunula is obliterated. The findings are associated with cirrhosis, chronic congestive heart failure, and chronic renal failure. The condition can also result from normal aging, viral hepatitis, T2 diabetes mellitus, and tuberculoid leprosy.
Half and Half Nails
Also called Lindsay’s nails are characterized by a proximal white, ground-glass-looking nail plate and distal pink, red or brown nail plate, with the latter occupying at least 20-60% of the total length of the nail. The condition mainly affects fingernails and less often toenails. Distinguished from Terry’s Nails in which the distal pink, red, or brown zone occupies less than 20%. The proximal white band is believed to result from chronic anemia, an increase in the thickness of the capillary wall, and overgrowth of connective tissue between the nail plate and the underlying structure with a reduction of blood flow in the subpapillary plexus. The distal pink, red or brown coloration is caused by increased melanin deposition, possibly stimulated by uremic or other toxins or by stagnant venous return. As the two bands do not move with the growth of the nail so the nail bed is likely to be the cause of the primary pathologic site. Lindsay’s nails occur in 8-50% of chronic renal failure patients, especially those who are on hemodialysis. The condition may also occur in association with Crohn’s disease, Kawasaki’s disease, liver cirrhosis, Bechet disease, yellow nails syndrome, Type 2 diabetes, pellagra, Zinc deficiency, and medications (such as isoniazid, chemotherapeutic agents). Lindsay’s nails may also be idiopathic and occur in healthy individuals. A longitudinal half and half nail also described. Usually occur on thumbs or toes. The cause may be trauma or unknown.
Infections of Nails
Onychomycosis is an infection of the nails caused by dermatophytes, yeast, or molds. Dermatophytes are fungi that can easily attack skin, hair, and nails due to their keratinolytic enzymes. Predisposing factors are a familial history, diabetes, immunosuppression, and trauma to the nails. Primary dermatophyte infections occur in four main patterns, that is distal and lateral subungual onychomycosis, superficial white onychomycosis, proximal subungual onychomycosis, and total dystrophic onychomycosis. The nail plate gets Brown, yellow, orange, or white discoloration, thickened due to subungual hyperkeratosis, and onycholysis is common.
Pseudomonas Nail Infection
Green or black discoloration of under surface of nail plates. Onycholysis is usually present and Paronychia is common. There is little discomfort or inflammation in pseudomonas infection of a nail. A few drops of a mixture of one part chlorine bleach and four-part water under the nail three times a day cures the condition. Vinegar can be used also.
The rapid onset of painful, bright red swelling of the proximal and lateral nail fold may occur spontaneously or may follow trauma or manipulation.
Inflammation of proximal and lateral nail folds that may be colonized by candida. Nail folds are often red swollen and tender. Significant contact irritant exposure is a major cause. People whose hands repeatedly get wet (baker, dishwasher, housemaids) are at increased risk. Typically many or all fingers are involved simultaneously. The cuticle separates from the nail plate leaving the space between the proximal nail fold and the nail plate exposed to infections. The process is chronic and responds slowly to treatment.
Nail Disorders Associated with Skin Conditions
Nail involvement usually occurs simultaneously with psoriatic skin disease but it may occur as an isolated finding. More than 50% of patients suffer from pain, and many are restricted in their daily activities. Small punched-out depression is seen as pitting on the nail plate. Nail plate cells are shed in the same way as psoriatic scales. Many other cutaneous diseases also cause pitting, such as Eczema, chemical dermatitis, Reiter’s syndrome, Sarcoidosis, Alopecia areata, and fungal infections or it may occur as an isolated finding in normal variation. Psoriasis of the nail bed may cause localized separation of the nail plate. Nails detach in an irregular manner. Nail plates turn yellow simulating a fungal infection. Cellular debris and serum may collect in the space. The brownish yellow color observed through the nail plate looks like a spot of oil. Psoriasis of the entire nail matrix may cause grossly deformed nails.
Approximately 25% of patients with nail’s lichen planus have lichen planus in other sites before or after the onset of nail lesions. Metal allergies have been implicated. The matrix, nail bed, and nail folds may be involved in producing a variety of changes. Inflammation of the matrix cause ridging and grooving of the nail plate. A pterygium, caused by adhesion of a depressed proximal nail fold to the scarred matrix may occur after intense matrix inflammation. Onychomycosis may be confused with lichen planus.
The separation usually starts distally but can start proximally. The detached nail plate appears white due to the air between the nail plate and the nail bed. Patients may have a history of using irritants (e.g. Nails cosmetics, soaps, and detergent), ill-fitting shoes, long nails, or trauma. Onycholysis may also be associated with psoriasis, fungal infection, yellow nail syndrome, contact dermatitis, medications (such as doxycycline), thyroid disease as well as many environmental causes. The separated nail should be clipped off and kept dry.
When an injury to a nail occurs, a hemorrhage (blue or black ) often forms under the nail plate. It usually grows out with the nail. Any persistent hemorrhage needs to be distinguished from subungual melanocytic lesions, especially melanoma.
White spots in the nail plate (Leukonychia Punctata) are very common, possibly resulting from cuticle manipulation or other mild trauma. The spots or bands may appear at the lunula or may appear spontaneously on the nail plate and subsequently disappear or grow out with the nail.
Distal plate splitting or peeling resembling scaling of dry skin. Calcium deficiency or repeated water immersion and frequent use of nail polish remover dehydrate the nails. A moisturizer may be applied and then cover with gloves or soaks.
Triangular strips of skin may separate from the lateral folds, particularly during the winter months. Attempts at removal cause pain. Separated skin should be cut. Constant lubrication of the fingertips with skin creams (e.g. Aquaphor ointment) and avoidance of repeated hand immersion in water are helpful.
Ingrown toenails or fingernails are common. The large toe is frequently affected. The nail pierces the lateral nail fold and enters the dermis where it acts as a foreign body. The penetration causes inflammation pain and swelling. Ingrown toenails are caused by poorly fitting shoes, improper or excessive trimming of nails, or trauma.