Bony proliferation of terminal toe phalanges in psoriasis: the "ivory" phalanx.

Twenty-eight per cent of our patients with psoriatic arthritis involving the feet demonstrated osseous proliferation and increased radiodensity of the terminal phalanges. This sign, the "ivory" phalanx, is a poorly recognized radiographic manifestation of the disease, but is particularly important in the absence of articular abnormality or of resorption of the tufts. It is almost invariably associated with nail diseases of the same digit.