Koilonychia (spoon-shaped nails) is the opposite of clubbing. The nail is firmly attached to bone by vertical dermal connective tissue bundles in the subungual area which bond directly to the bony periosteum. In the early stages of koilonychia there is flattening of the nail plate. Later, the edges become everted upwards and the nail appears concave, giving rise to the characteristic ‘spoon’ shape (Figures 2.8–2.11). In mild cases the water test may enable a drop of water to be retained on the nail plate. The subungual tissues may be normal, or affected by hyperkeratosis at the lateral and/or the distal margin.

Koilonychia is more often due to local rather than systemic factors

1 In neonates and in infancy, koilonychia is a temporary physiological condition (Figures 2.12, 2.13). There is a proven correlation between koilonychia and iron deficiency (with normal haemoglobin values) in infants.

2 Koilonychia is a common manifestation of the rare Plummer-Vinson syndrome in association with anaemia, dysphagia and glossitis.

3 When subungual keratosis accompanies koilonychia, psoriasis should be considered, as well as occupational causes, which may be relevant in those who work with cement, or in car mechanics whose hands suffer constant immersion in oil, for example.

4 Koilonychia may result from thin nails of any cause (old age, peripheral arterial disease and so on).

Figure 2.8

Koilonychia or ‘spoon-shaped’ nail; thin nail variety.

Figure 2.9

Koilonychia—distal view with some terminal traumatic whitening.

 

 

Figure 2.10

Koilonychia—severe variety, of many nails. Involvement of the first three nails is a plea for an occupational cause.

 

 

 

 

 

 

 

Figure 2.11

Koilonychia—transverse and longitudinal curvature evident.

5 Soft nails of any cause (mainly occupational) may also cause this condition.

6 Hereditary and congenital forms (Figures 2.14–2.16) are sometimes associated with other nail signs such as leukonychia.

The most common causes of koilonychia are probably occupational softening and iron deficiency (Table 2.2) Occupational koilonychia is often associated with mild nail-plate surface abnormalities and nail plate discoloration.

Figure 2.12

Koilonychia—temporary type of early infancy.

 

 

 

 

 

 

 

Figure 2.13

Physiological koilonychia and thinning in the toe nails of a 3-month-

old infant.

 

 

 

 

Figure 2.14

Severe congenital koilonychia.

Figure 2.15

Koilonychia in hereditary ectodermal dysplasia.

 

 

 

 

Figure 2.16

Congenital koilonychia associated with total leukonychia.

Common causes of koilonychia

Physiological

• Early childhood (Figures 2.12–2.13)

 

Idiopathic

Congenital

• LEOPARD syndrome
• Ectodermal dysplasias (Figure 2.15)
• Trichothiodystrophy
• Nail-patella syndrome
• Acquired
• Metabolic/endocrine
• iron deficiency
• acromegaly
• haemochromatosis
• porphyria
• renal dialysis/transplant
• thyroid disease
• Dermatoses
• alopecia areata
• Darier’s disease
• lichen planus
• psoriasis
• Raynaud’s disease
• Occupational
• contact with oils, e.g. engineering industry
• Infections
• onychomycosis
• syphilis
• Traumatic
• toes of rickshaw pullers
• Carpal tunnel syndrome

 

Figure 2.17

Transverse overcurvature showing the three subtypes: (a) pincer or trumpet nail; (b) tile-shaped nail; and (c) plicatured nail with sharply angled lateral margins.