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).