Following embryonic differentiation, the human nail grows continuously throughout life at a rate of about 0.5 to 1.2 mm per week, slowing down with age. Trauma appears to stimulate growth, while immobilization retards the process. Toenails appear to grow at a third to a half the rate of fingernails, and full replacement from base to free edge might take anywhere between 12 and 18 months. Slowing of nail growth is also a feature of malnutrition, arterial insufficiency, systemic infections, and intercurrent acute illness; the latter typically produces metabolic growth arrest, or Beau’s lines.
Cigarette smoking affects nail growth and morphology in several ways; the most common manifestation is the yellow nail or the nicotine sign. Such a yellow pigmentation, though more generalized, has been seen in the endogenous dyschromias due to toxic reaction (long-term tetracycline therapy), infectious (scopulariopsis), metabolic (amyloidosis, diabetes, jaundice), and idiopathic (yellow nail syndrome) causes. The yellow nail syndrome describes a yellowish green discoloration of the nails associated with lymphedema, facial edema, lymphatic hypoplasia, and a characteristic slowing of nail growth. A host of pulmonary abnormalities has been described with the syndrome, including pleural effusions, bronchitis, bronchiectasis, and malignant pulmonary neoplasms. When the yellow staining is accompanied by clubbing in a long-term smoker, a diagnosis of bronchopulmonary suppuration or malignancy is suggested. Long- term smokers can also develop a progressive curving of their fingernails associated with pulp atrophy, to which the term “breaking,” or claw nail, has been applied, not to be mistaken for clubbing.
An acute illness, such as a CVA, interrupts the process of nicotine staining, and with continuing nail growth, a line of demarcation forms between the distal, pigmented, yellow nail and the proximal, newly formed, pink nail with a white lunule. We propose the term “harlequin nail” for this curious physical sign. The word “harlequin” has at least five meanings; we prefer the meaning “fancifully varied in color, decoration, etc.” the “half-and-half” nail described by Lindsay is superficially similar, occurring in patients with chronic renal failure and rarely in patients receiving cytotoxic therapy. The pigmentation in this condition, unlike that in the “harlequin nail,” appears to be located in the nail bed rather than the nail plate and hence does not grow out with the nail. levitra plus
In this era of increasingly complex diagnostic technology and therapeutic intervention, there continues to be interest and a growing literature on bedside diagnosis. The “harlequin nail” is a simple clinical sign that provides useful information on the patient and that underscores the rewards of careful bedside examination.