Sir,

Retronychia is an uncommon nail disorder characterized by the ingrowth of the proximal nail plate into the nail fold. The most frequent triggers are repeated minor trauma, systemic illness, and disrupting the nail’s longitudinal growth and the vertical growth of the new plate into the proximal nail fold [1].

A 52-year-old female patient consulted for a two-month history of absent nail growth in the left hallux. Dermatological examination revealed a localized onychopathy, a proximal nail fold with erythema and edema, the absence of the cuticle, and nail plate discoloration (Fig. 1). Dermoscopy revealed the absence of the cuticle, erythema of the proximal nail fold, and xanthonychia of the nail plate (Fig. 2). She recalled a similar incident in the same toenail fifteen years ago; she practices yoga and swimming twice a week, which may contribute to recurrent mechanical stress on the affected nail. The diagnosis of retronychia was made, and the avulsion of the nail plate was performed.

	Figure 1: Erythema at the level of the proximal fold of the fi rst toenail of the left foot.
	Figure 2: Close up of the onychopaty.
	Figure 3: Dermoscopy showing the absence of the cuticle, yellowish dyschromia of the nail, and erythema of the proximal fold.

Repetitive hyperextension of the hallux during yoga and prolonged maceration from swimming were potential etiological factors in this case [2]. Hence, the most common causes are repetitive microtrauma, strenuous sports, spontaneous or acute trauma, and even anatomical factors such as congenital malformation or systemic disorders like arthritis [3]. To prevent recurrence and unnecessary procedures, awareness of these predisposing factors is crucial.

Retronychia is frequently underdiagnosed or mistaken with other nail conditions, leading to inappropriate management. Clinical diagnostic criteria include the inflammation of the proximal nail fold, xanthonychia, granulation tissue under the nail fold, thickening of the proximal portion of the nail plate, and the interruption of nail growth [3,4]. Ultrasonography may play an important role in demonstrating the distinctive layering of the nail plates, which is also observed in dermoscopy [5].

Treatment options range from conservative treatments, such as taping, orthoses, and topical steroids in early stages, to nail avulsion, which continues to be the preferred treatment [3,5,6]. In addition to highlighting the importance of preventive measures in physically active adults to lower recurrence risk, this case underscored the role that mechanical stress plays in the etiology of retronychia.

REFERENCES

1.Rallis E, Nasiopoulou A, Verros C, Papadavid E. Retronychia:A common but underdiagnosed entity. J Am Podiatr Med Assoc. 2018;108:375-8.

2.Piraccini BM, Uribe PS. Dermoscopic patterns of inflammatory nail diseases. Int J Dermatol. 2024.

3.de Almeida HL, Siqueira AL, Rocha NM, Bonamigo RR. Retronychia:Clinical and pathological findings. An Bras Dermatol. 2022;97:28-31.

4.Lee DK, Lipner SR. Optimal diagnosis and management of common nail disorders. Ann Med. 2022;54:694-712.

5.Elizalde-Jiménez IG, Castanedo-Cázares JP, Ocampo-Candiani J, González-Ramírez R. Retroniquia, una onicopatía poco reconocida. Reporte de dos casos. Dermatología Cosmética, Médica y Quirúrgica. 2021;19:258-64.

6.Grover C, Jakhar D. Retronychia:Diagnostic challenges and management considerations. Int J Surg Case Rep. 2024;110478.