Beau lines, onychomadesis, and retronychia: A unifying hypothesis

Seasonal Onychomadesis of the Great Toes

“…Traumatic onychomadesis is generally associated with obvious, sometimes dramatic trauma, such as repetitive friction from long-distance running, wrist and arm fracture, or fingertip crush injury [2,10]. The use of ill-fitting, closed-toe shoes with a narrow toe box in the winter is a logical source of recurrent, seasonal toenail trauma.…”

“…As the distal portion of the nail grows out, the separated proximal portion is painlessly shed [1]. The pathogenesis of onychomadesis is similar to that of Beau's lines where transverse depressions result from a thinned nail plate due to slowing or disruption of cell growth within the matrix [2]. …”

“…A variety of causes of Beau's lines and onychomadesis have been identified: trauma, infectious disease, autoimmune, neonatal, systemic disease, hereditary, medication induced, and idiopathic [2]. In all of these conditions, an insult to the nail matrix results in an alteration of nail growth.…”

Ultrasonographic Criteria for Diagnosing Unilateral and Bilateral Retronychia

“…Retronychia is a nail disorder characterized by embedding of the proximal nail plate into the proximal nail fold, which clinically appears as an apparent halt to nail growth with a chronic proximal paronychia . It may be an underestimated condition that can appear after or concomitant to a severe illness, can be related to stress‐relevant situations, can be secondary to trauma, including sports injuries, or can appear as an idiopathic episode . Additionally, it has been reported that retronychia may have a similar etiology as Beau lines and onychomadesis.…”

“…Additionally, it has been reported that retronychia may have a similar etiology as Beau lines and onychomadesis. Thus, in addition to the previously described potential conditions, it can include stress in utero, medications, and hereditary causes, among others …”