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Koilonychia, concavity, or spoon-shaped nails, caused by thinning and softening of the nail plate. This classical nail disorder of

iron deficiency

is associated with postcricoid webbing. It is also seen in

hereditary hemochromatosis

and

porphyrias

. Clubbing, possibly due to reduced

ferritin

opening up the nail-bed arteriovenous anastomoses. It is traditionally associated with suppurative lung disease and cyanotic heart disease, but also occurs with celiac disease, Crohn’s disease, and

Hodgkin disease

involving the lungs.