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A 38-year-old male patient who works in a conveyor manufacturing plant sees you for an upper respiratory tract infection. During your examination, you note that he has koilonychia (spoon nails) of the thumb and second finger of his right hand. (See photograph.) He is right-hand dominant. There is no involvement of the left hand. He has no symptoms related to the koilonychia. The most likely cause of this patient's condition is:

1. Undiagnosed iron deficiency anemia
2. Normal variant from birth
3. Nail-patella syndrome
4. Trauma or exposure to chemicals at work
5. Collagen vascular disease

Answer: D

DISCUSSION

Koilonychia is characterized by concave-shaped nails. The edges of the nails elevate, giving the nail a spoon-shaped appearance. Koilonychia usually has few symptoms and is generally an incidental finding. Patients who do complain of their nails usually do so for cosmetic reasons.

It is well known that koilonychia may be associated with systemic disease. Koilonychia is associated with iron deficiency anemia, hemochromatosis, collagen vascular disease (Raynaud's, systemic lupus erythematosus) and other endocrine (thyroid dysfunction) and cardiac diseases (impaired peripheral circulation). It is a transient normal finding in infants and is usually self-limiting. Koilonychia is also associated with some inherited diseases, such as nail-patella syndrome. However, in these cases it is not an isolated finding. Other findings of this autosomal dominant disorder include easily dislocated or absent patellas, glaucoma and renal and skeletal abnormalities (elbow deformities, accessory posterior iliac horns).

What is not as well known is that koilonychia may also be work related. It has been associated with exposure to oils, solvents and trauma. In one study of auto mechanics, the incidence of koilonychia was found to be 5.3 percent. Koilonychia is also common in hairdressers. This has been related to the chemicals used in permanent waves. Koilonychia has also been found in mushroom-growers, slaughterhouse workers, cement workers and rickshaw (cart) pullers.

Whenever koilonychia is found on physical exam as an isolated finding, the physician may consider an extensive work-up, looking for systemic disease. In addition to a complete family history, dietary history and physical examination, laboratory studies may include complete blood count, blood urea nitrogen, creatinine, urinalysis, antinuclear antibody, sedimentation rate and rheumatoid factor. However, a complete occupational history may be more revealing. The patient described above worked assembling conveyors. His job consisted of applying nuts to bolts with his right hand. The nuts were coated with oil to prevent rust. He had performed this job for several years.

Koilonychia as an isolated finding may be a sign of systemic disease. However, acquired koilonychia may be a better indicator of an occupational disease. This is especially true when the koilonychia only affects the thumbs and first fingers or involves only the dominant hand.

References:

1. Alanko K, Kanerva L, Estlander T, et al. Hairdresser's koilonychia. Am J Contact Dermat 1997; 8(3):177-178.
2. Dawber R. Occupational koilonychia. Clin Exp Dermatol 1977; 2(2):115-116.
3. Fawcett RS, Linford S, Stulberg DL. Nail abnormalities: clues to systemic disease. Am Fam Physician 2004; 69(6):1417-1424.
4. Fawcett RS, Stulberg DL. The adult working years: common skin findings in systemic disease. Clin Fam Pract 2003; 5(3):667-689.
5. Pedersen NB. Persistent occupational koilonychia. Contact Dermatitis 1982; 8(2):134.

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