We have recently experienced this rare condition in a premature baby born at 25 weeks gestation. At the age of 56 days, it was noticed that he had developed odd looking fingernails (two on each hand). He did not have any other mucocutaneous abnormalities or family history of similar conditions.

A culture of his nails was reported as negative for bacterial and fungal infections, and the diagnosis of pachyonychia congenita was made on the basis of nail morphology.

Pachyonychia congenita is a group of uncommon hereditary keratin disorders characterised by hypertrophic nail dystrophy and associated ectodermal features.¹ However, it can be manifested with only nail affection.² The nails are thickened and tubular, projecting upward at the free edge to form a conical roof over a mass of subungual keratotic debris (fig 1).

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Figure 1

 Thickened nail characteristic of pachyonychia congenita.