Red Nails

The normal color of the nail bed is light red or pink. There are some pathologic processes where a portion of the nail unit is red. Red spots in the lunula (Figures 69 and 70) are seen in several disorders including psoriasis, lichen planus, alopecia areata. Diffuse reddish lunula are seen with systemic lupus, rheumatoid arthritis, cardiac disease and others.

Glomus tumor is seen as a red macule beneath the nail. Carbon monoxide poisoning, systemic lupus erythematosus and polycythemia cause red changes in the nail unit.

Blue Nails

Blue nails can result from medications such as minocycline (Figure 67), antimalarials, phenothalein, bleomycin, and phenothiazines. Wilson’s disease and argyria (Figure 68) can be associated with blue nails.

Yellow Nail Syndrome

In the yellow nail syndrome, the nail changes are characterized by yellow, slow-growing nails with absent lunula and cuticle (Figure 65). Yellow nail syndrome is usually associated with a pulmonary problem such as pleural effusion, bronchiectasis or chronic sinus infection. The underlying pathological process is thought to be related to impaired lymphatic drainage.

enamel. The nail plate is stained by the dye in nail polish (Figure 66). Some medications, including tetracycline, can cause a yellow discoloration of the nail.

Longitudinal Grooves

Longitudinal depressions can occur in the nail as a result of a space-occupying lesion in the nail fold overlying the nail matrix. The mass presses on the matrix and nascent nail resulting in a depressed deformity. Lesions such as myxoid cyst (Figure 14) and fibroma (Figure 15) can cause the groove. When the mass is removed, the nail usually grows in normally (see myxoid cyst).

Leukonychia

Leukonychia is the name given to white nails. The condition can be congenital or acquired, complete or partial, and true or apparent. Punctate and striate leukonychia (Figure 13) is a common partial leukonychia. It is due to microtrauma of the matrix near the proximal nail fold that causes parakeratotic cells to form in the nail plate. These white spots grow out with the nail.

Koilonychia

Koilonychia occurs when the free edge of the nail is everted, resulting in a concave ‘spoon nail’. There are many causes of koilonychia ranging from anemia and thyroid abnormalities to a normal finding in some children (Figure 12)

Habit Tic Deformity

Habit tic deformity has the appearance of parallel horizontal grooves in the nail plate, as the result of repetitive minor trauma to the proximal nail plate and lunula. The defect formed by the chronic picking and rubbing and the grooved appearance of the nail have been described as resembling a washboard. Thumbs are most commonly involved and the lunula is usually enlarged. The nail often grows in normally when the chronic picking ceases (Figures 10 and 11).

White Nails Disease

The term leukonychia is used to describe nails that appear white. It can be divided into several categories: partial versus complete, true versus apparent, and congenital versus acquired.

True leukonychia occurs when the actual nail plate is white due to alterations of the nail plate keratinocytes. Apparent leukonychia is due to alterations in the nail bed, matrix or hyponychium that give the nail the white appearance.

Punctate leukonychia is common and results from minor nail trauma to the nail in the vicinity of the nail matrix, resulting in nucleated keratinocytes in the nail, which appear as small white areas (Figure 60). An extension of punctate leukonychia is transverse leukonychia, also due to trauma to the matrix, often during manicuring. These narrow white lines are often parallel with the proximal nail fold and grow out with the nail. True leukonychia can be seen in some types of onychomycosis and psoriasis.

Apparent leukonychia describes a nail that looks white but is, in fact, normal in color. Onycholysis is an example of apparent leukonychia because the white appearance is due to air beneath the nail. When the nail is removed in apparent leukonychia, the nail plate is of normal color (Figure 61). Three examples of pseudoleukonychia are Terry’s nail, Muehrche’s lines, and half-and-half nails. These conditions are due to nail bed whitening.

Terry’s nails (Figure 62) appear milky white and opaque from the lunula to the onychodermal band. Terry’s nails are seen in patients with hepatic dysfunction and cirrhosis. There have been reports of Terry’s nails in patients with chronic congestive heart disease, type 2 diabetes mellitus, and aging. The Terry’s nails of congestive heart failure may also be pink, a different presentation from the white nails of liver disease.

Muehrche’s lines (Figure 63) are white horizontal bands that are parallel to the lunula and separated by pink bands. This condition occurs when the serum albumin is low, and disappears when the albumin levels return to normal. Muehrche’s lines occur in patients with renal failure and/or hemodialysis.

The half-and-half nail has a proximal, opaque, white portion that obscures the lunula and a distal red/brown color (Figure 64). It also occurs in patients in renal failure and on hemodialysis.

Other causes of true leukonychia are onychomycosis and psoriasis.

Chromonychia

Chromonychia is the presence of abnormal nail color. The natural nail plate is translucent and derives its apparent color from the underlying structures. Certain internal diseases and medications can cause color abnormalities in the nail plate. External factors can stain and discolor the nail plate. When the pigmentation is caused by external factors, the change in pigmentation parallels the contour of the proximal nail fold and, when caused by internal factors, the change usually follows the lunula contour.

Brachyonychia

In brachyonychia, or short nails, the longitudinal dimension of the nail is shorter than normal, giving the fingernail an unusually broad appearance. This can occur as an isolated finding and there may be shortening of the terminal phalanx. The thumbs are commonly affected (racket nails) and this may be familial (Figures 7 and 8).

Beau’s lines

Beau’s lines are horizontal grooves in the nail plate that represent an arrest or slow-down in the growth of the nail matrix. A severe medical event such as surgery, allergic reaction to medication or serious trauma to the system can trigger Beau’s lines. The depth and width of the line speak to the abruptness and duration of the event. Beau’s lines move distally as the nail grows over time (Figure 6).

Anonychia

Anonychia is the absence of nail. It can occur as the end result of scarring (onychatrophy) (Figure 4) and in congenital disorders, often when there is malformation of the corresponding digit (Figure 5).

Nail Biopsy

When history and clinical features alone do not yield a diagnosis, a biopsy of the nail should be considered. The location of the nail biopsy is dependent upon which part of the nail unit is responsible for the pathological features of the nail. When the nail plate is abnormal, the pathological process is often located in the nail matrix or is a space occupying lesion in the nail fold. Nail bed and nail fold changes require biopsy of the appropriate area. If the clinician is not experienced or comfortable with the procedure of nail biopsy, a referral to a dermatologist should be considered.