Vertically growing nail - A rare entity.

Sir,

The reason why nails grow flat, rather than vertical, has been a matter of debate. There have been reports of ectopic nails growing vertically. We herein report an interesting and unusual case of a normally placed nail growing vertically.

A 16-year-old female presented with a vertical growth of the nail on the left index finger since childhood. The patient underwent two surgical nail excisions in the past, in the hope of getting rid of the vertical growth; however there was no change. The last surgical excision was two years earlier. There was no history of trauma, nail infection, or any significant family history.

On examination, the left index finger nail showed a vertical growth of 2.5 cm [Figures 1 and 2]. The nail plate was thickened, brownish grey with loss of normal convexity and appeared conical in shape with a broad base and tapered rounded apex. The surface showed longitudinal ridges with pits. The pits were small, shallow, randomly placed, and numerous at the lower half of the nail. The proximal nail fold showed a brownish black discoloration with scaling, whereas the lateral nail folds appeared thickened with blackish discoloration. The hyponychium showed the presence of greyish white debris. The nail bed was not visualized. There was no visible bony deformity. Other nails were normal. Cutaneous, hair, and dental examinations were unremarkable.

Figure 1

Left index finger showing a normally placed vertically growing nail with a thickened brownish grey nail plate. The surface shows longitudinal ridges and numerous, small, shallow, randomly placed pits. Discoloration of the nail folds is observed

Figure 2

Top view of the left index finger showing vertical growth of the nail with brownish black discoloration of the proximal nail fold. Other nails appear normal

Nail scrapings for potassium hydroxide and fungal culture were negative. A radiography of left hand revealed mild scalloping of the tip of the terminal phalanx of the index finger [Figure 3]. Because the patient had undergone two nail excisions in the past, she did not consent for nail biopsy.

Figure 3

Radiography of left hand anteroposterior (left) and lateral (right) views revealed mild scalloping of the tip of the terminal phalanx of the left index finger with no bifid anomaly present. The other bones and joints visualized were normal

The reason why nails grow flat, rather than as heaped up keratinous masses or vertically is debatable. It is hypothesized that the guiding restraint of the proximal nail fold, the inducting influence of the underlying phalanx, containment by the lateral nail folds, the adherence of the nail plate to the nail bed, and the direction of cell differentiation are all contributory factors to the flat growth of the nail.

After extensive review of the literature, case reports of ectopic nails growing vertically have been described,[1234] but the vertical growth of a normally placed nail apparatus has not been described. It was hypothesized by Kligman that the proximal nail fold is responsible for the outward growth of the nail.[1] This view was questioned by Baran as he could not find any case of a normal nail growing on an abnormal or absent phalanx[5]; therefore, concluding that an underlying normal phalanx was responsible for the outward growth. Kato, however, refuted both these hypotheses stating that the absence of a proper nail bed promoted the upward growth of a nail plate, instead of its outward growth.[4]

Our patient had normal proximal nail folds, which however did not seem to play any role in assisting the nail plate to grow outward. Besides, radiologically the underlying bone showed no bifid anomaly. Probably, the nail bed did not play its role of adhering to the nail plate and assisting it in its growth outward, thus leading to the upward growth of the nail in our case.