A rare benign nail tumour originating in the nail matrix characterised by localised or diffuse thickening of the nail plate, increased transverse or longitudinal overcurvature, a yellow longitudinal band of variable width, swelling of the proximal nail fold, multiple splinter haemorrhages and the presence of honeycomb-like cavities in the distal margin of the nail plate. Nail dystrophy and dorsal pterygium may be associated. Occasionally a pigmented lesion has been reported. [from
SNOMEDCT_US]