Nail psoriasis or trachyonychia? Can dermoscopy differentiate them?

Trachyonychia is a disease of the nail matrix that can present as either opaque or shiny trachyonychia. Although it is often idiopathic, it can be associated with conditions such as alopecia areata (AA), psoriasis, and lichen planus. Isolated nail psoriasis (NP) can mimic trachyonychia, making diagnosis challenging. Dermoscopy, a non-invasive imaging technique, has proven useful in identifying NP features. This report presents two cases: one with isolated psoriatic trachyonychia and another with AA-associated trachyonychia. In both cases, jagged erythema and teardrop-shaped spots on the lunula were observed, with the latter being described for the first time in trachyonychia literature. These findings suggest a potential link between inflammation and nail matrix pathology, warranting further investigation.