Nail Signs of Systemic Disease

Beau Lines

Beau lines are transverse grooves in the nail plate that arise due to temporary suppression of nail growth within the nail matrix and occur during periods of acute/chronic stress and/or systemic illness ( Fig. 44-2 ). The precipitating event might be local trauma, paronychia, chemotherapeutic agents that are cytotoxic to the nail matrix, or abrupt onset of systemic disease. These grooves have also been described in association with rheumatic fever, malaria, pemphigus, Raynaud’s disease, and myocardial infarction, as well as following deep-sea dives. The distance of the Beau line from the proximal nail fold will give the clinician an estimate of the time of the acute stress, using average growth rates of 3 mm/month for fingernails and 1 mm/month for toenails.

Mees Lines

Mees lines are 1- to 2-mm wide horizontal parallel white bands (leukonychia striata), which span the width of the nail plate, usually affecting all fingernails. They are associated with arsenic poisoning in most instances and may be used to identify the time of poisoning, since they require about 2 months to appear on the fingernails following the initial insult. Mees lines have also been described in association with numerous acute systemic stresses, such as acute renal failure, congestive heart failure, ulcerative colitis, breast cancer, infections such as measles and tuberculosis, systemic lupus erythematosus, and with exposure to other toxic metals such as thallium. Leukonychia striata is also commonly associated with trauma to the nail matrix, such as from manicuring. The clinician can differentiate between leukonychia striata caused by trauma and that associated with systemic disease because in the latter the lines run parallel to the lunula, have smoother borders, are more homogeneous, span the width of the nail plate, and involve multiple nails. Mees lines are an example of true leukonychia, in which there is abnormal keratinization of the underlying nail matrix, resulting in parakeratosis within the nail plate and an opaque appearance on examination. The white discoloration is unaffected by pressure, and the opacity will move distally as the nail grows out.

Pitting

Nail pitting involves small depressions in the nail plate due to aberrant keratinization within the proximal nail matrix, resulting in clusters of parakeratotic cells within the nail plate. Nail pitting is a nonspecific finding and is associated with diseases affecting the proximal matrix, such as psoriasis, psoriatic arthritis, and reactive arthritis ( Fig. 44-3 ). It has also been reported in association with alopecia areata, atopic dermatitis, Langerhans cell histiocytosis, and junctional epidermolysis bullosa.

Longitudinal Pigmented Bands (Melanonychia)

Longitudinal melanonychia refers to vertical bands of brown-black pigment in the nail plate and may be caused by blood from trauma, bacteria, fungus, HIV infection, drugs, endocrine disorders, exogenous pigment, or melanin. Longitudinal pigmented bands associated with internal disorders are usually present in multiple nails, and have been reported in Addison’s disease, systemic sclerosis, leprosy, and following bilateral adrenalectomy for Cushing’s disease. Longitudinal pigmented bands may also be caused by many medications, including bleomycin, fluoride, melphalan, cyclophosphamide, doxorubicin, paclitaxel, antimalarials, and zidovudine ( Fig. 44-4 ). Dark transverse bands, on the other hand, may be associated with quinacrine, doxorubicin, and cyclophosphamide. Nitrogen mustard and methotrexate may produce diffuse hyperpigmentation of the nail plate.

Melanin is a pigment produced by melanocytes within the nail matrix and may be caused by benign processes such as benign melanocytic activation, lentigines, and nevi, or by malignant conditions such as melanoma. Fortunately, benign melanocytic activation and benign nevi are the most common causes of longitudinal melanonychia in adults and children, respectively.

Laugier–Hunziker syndrome is a rare acquired disorder characterized by diffuse gray to dark-brown macules, most predominantly located on the lips and oral mucosa. About 50% of patients also have accompanying longitudinal melanonychia of their fingernails.

Brittle Nails

Brittle nails may be a component of the brittle nail syndrome, which is a heterogeneous abnormality characterized by roughness of the surface of the nail plate, fragility or raggedness of the distal nail, splitting, and peeling. While the pathogenesis is not well understood, it is associated with an abnormality of keratin, keratin-associated proteins, water, and/or lipid content. There is also impairment of intercellular adhesion of the corneocytes of the nail plate. The majority of cases are idiopathic, but some are associated with systemic diseases including arterial insufficiency, Raynaud’s phenomenon, iron deficiency, bronchiectasis, diabetes mellitus, osteoporosis, amyloidosis, hyper- and hypothyroidism, gout, tuberculosis, hypopituitarism, and sarcoidosis.

Koilonychia

Koilonychia is defined by a concave nail plate with eversion of distal and lateral edges, creating a nail that looks like a spoon. Fingernails are affected more often than toenails, and the second and third fingernails are the most commonly affected. The pathogenesis is not well understood, but may involve the absorption and distribution of iron and protein, or the position of the distal matrix in relation to the proximal matrix.

Koilonychia was originally described in association with iron-deficiency anemia (Plummer–Vinson syndrome) ( Fig. 44-5 ), and the condition normalizes with iron supplementation. It has subsequently been reported in normal children and as a temporary finding in infants, as well as existing in hereditary (autosomal dominant), acquired, and idiopathic forms. The acquired type comprises the largest group of patients with koilonychia and is most commonly seen in psoriasis, fungal infection, distal ischemia (e.g., Raynaud’s phenomenon), and trauma. It may also occur in association with porphyrias, hemochromatosis, and occupational exposures (chemical exposure in hairdressers and exposure to organic solvents). Koilonychia has also been reported in association with carcinoma of the upper gastrointestinal tract.