ABSTRACT
Glomus tumor is a benign tumor originating from glomus bodies and is more frequent in the hand, mainly in the subungual region. It is normally a solitary and painful lesion, seeing through the nail plate as a reddish-blue spot. Usually, the pain is paroxysmal and disproportionate compared to the mild clinical picture. The pain disappears when a tourniquet is applied. Transillumination test, Dermoscopy, Ultrasonography with Doppler, Computed Tomography, and Magnetic Resonance Imaging are useful to define the diagnosis. In some cases, glomus tumor appears as longitudinal erythronychia that does not reach the distal margin, especially in the presence of small masses. Nail plate alterations, such as onycholysis, thinning, and splitting of the nail can also be seen in cases of large masses. Dermoscopy shows paradoxically a whitish nail bed area because of vascular compression by the tumor ( Figure 17.1 ).
