See Also
Common Skin Diseases
The primary purpose of the nail is protection. Abnormalities of the nail are often caused by skin disease and infection (most often fungal) but may also indicate more general medical conditions. This discussion does not address localized trauma or nail infections but offers examples of nail abnormalities that may occur with systemic disease.
Check to see whether the nails are normal by looking at the following (Figure 1):
Softness and flexibility of free edge;
Shape and color;
Growth rate (about 6 months from cuticle to free edge). Time of events can be estimated from location.
Clubbed Fingernails
clubbing involves a softening of the nail bed with the loss of normal angle between the nail bed and the fold, an increase in the nail fold convexity, and a thickening of the end of the finger so it resembles a drumstick.
To determine whether nails are clubbed, have the patient place both forefinger nails together and look between them. If you can see a small diamond space between them (Schamroth's window) then the nails are not clubbed (Schamroth's sign) (Figure 2).
Figure 2. Schamroth's sign.
Causes of clubbing ( (Figure 3):
Pulmonary and cardiovascular causes (80%)
Lung cancer, pulmonic abscess, interstitial pulmonary fibrosis, sarcoidosis, beryllium poisoning, pulmonary arteriovenous fistula, subacute bacterial endocarditis, infected arterial grafts, aortic aneurysm
Gastrointestinal causes (about 5%)
Inflammatory bowel disease, sprue, neoplasms (esophagus, liver, bowel)
Hyperthyroidism (about 1%)
Note: Chronic obstructive pulmonary disease does not cause clubbing.
Figure 2. Schamroth's sign.
Koilonychia Koilonychia are spoon-shaped concave nails
Causes include the following:
Iron deficiency;
Diabetes mellituS
In 1846, Joseph Honoré Simon Beau described transverse lines in the substance of the nail as signs of previous acute illness.. The lines look as if a little furrow had been plowed across the nail. Illnesses producing Beau's lines include Severe infection;
Myocardial infarction;
Hypotension, shock;
Hypocalcemia; and
Surgery.
Figure 5A. The location of Beau's lines half way up the nail suggests illness 3 months ago.
Figure 5B. Two Beau's lines suggest illnesses about 2 months apart.
Thin Brittle Nails
Thin, brittle nails can indicate the following (Figure 6):
Metabolic bone disease (nail thinness is correlated with osteopenia);
Thyroid disorder;
Systemic amyloidosis (indicated by yellow waxy flaking); and
Severe malnutrition.
Figure 6. Note the thin nails in this woman with severe osteopenia.
Nail Pitting
Nail pitting -- small punctate depressions -- are caused by nail matrix inflammation, which can be the result of:
Psoriasis (random appearance of pits) (Figure 9);
Alopecia areata (geometric rippled grid) (Figure 10);
Eczema; and
Lichen planus.
Splinter Hemorrhages
Splinter hemorrhages are caused by hemorrhage of the distal capillary loop (Figure 22). Note the thickness of these areas. They are associated with the following:
Subacute bacterial endocarditis;
Systemic lupus erythematosus;
Trichinosis;
Pityriasis rubra pilaris;
Psoriasis; and
Renal failure.
Figure 22. Splinter hemorrhages tend to be fat.
Terry's Half and Half Nails
With Terry's half and half nails, the proximal portion is white (edema and anemia) and the distal portion is dark. These nails imply either renal or liver disease (Figures 23A, 23B).
Figure 23A. This example of Terry's half and half nails suggests liver disease (no brown lines).
White nails can be caused by anemia, edema, or vascular conditions (Figure 24). Consider the following:
Anemia;
Renal failure;
Cirrhosis;
Diabetes mellitus;
Chemotherapy; and
Hereditary (rare).
Processes Around the Nail
Paronychial Inflammation Paronychia is associated with separation of the seal between the proximal nail fold and the nail plate that provides entry for bacteria and leads to a localized infection of the paronychial tissues of the hands (Figure 29). Symptoms may include inflammation, swelling, and/or scaling.
Figure 29. Example chronic paronychial inflammation.
Periungal Telangeictasia Periungal telangeictasia is caused by dilated capillary loops and results in atrophy of the cuticle (Figure 30). It is strongly associated with collagen vascular disease, including the following:
Systemic lupus erythematosus;
Dermatomyositis (especially with Gotton's papules over knuckles); and
Scleroderma.
Figure 30. Example of periungal telangeictasia. Image courtesy of www.dermnet.com
Cases
The following are examples of patients in whom examining the fingernails may help identify their conditions.
KEY WORDS: clubbing,Schamroth's sign,Beaus line,Thin Brittle Nails,Nail Pitting Psoriasis,,Splinter Hemorrhages ,Subacute bacterial endocarditis;
Systemic lupus erythematosus,Terry's Half and Half Nails ,liver disease,White nails,Anemia;
Renal failure;
Cirrhosis;
Diabetes mellitus;Processes Around the Nail
Paronychial Inflammation ,Scleroderma nails
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