Fig. 21.

Retronychia at 24 MHz.

A. Power Doppler (left first toe) presents thickening and hypoechogenicity of the nail bed, fragmentation of the proximal nail plate (onychomadesis), thickening and hypoechogenicity of the proximal nail fold. There is a halo sign (*, hypoechoic band) in the periphery of the origin of the nail plate with hypervascularity of the proximal nail fold. B. Grayscale comparative views side-by-side show a decreased distance between the origin of the nail plate and the base of the distal phalanx on the left side (retronychia) versus the right side (4.8 mm vs. 9.2 mm).