Talon nail - a Fourth Type of Pincer Nail (Abstract)
Philip Fleckman MD
Dermatology Online Journal 7(2): 21J

A patient with an acquired, painful, fingernail dystrophy is presented. Extreme transverse curvature of the nail plates occured rapidly in association with onycholysis but no subungual debris. The dorsal surface of the nail plate was smooth. No bone, cutaneous, or infectious abnormalities were associated. The entity is distinct from pincer (arched, trumpet, omega) nail, where "transverse overcurvature that increases along the longitudinal axis of the nail and reaches its greatest proportion" distally is seen, and soft tissues can be pinched by lateral borders distally (Baran and Dawber, 1994). "In extreme cases [the ends of the nail plate] may join together, forming a tunnel; or they may roll about themselves taking the form of a cone." Affected nails may be shaped like claws. "Soft issue may disappear, accompanied by resorption of underlying bone." One sees "selective widening of the proximal region of the lateral matrix horns by juxta-articular osteophytes," while the shape of the distal matrix is unchanged. This results in the plate assuming a conical shape that rises above the nail bed. A tight bond beneath results in a traction osteophyte from the dorsum of the underlying phalanx. In the "tile nail" variant of pincer nail one sees "increased transverse curvature, while the lateral edges of nail remain parallel." In plicated (pleated) nail, the "surface [of the plate] remains flat, while lateral margins are sharply angled, forming vertical sides that are parallel." Pincer nails may be inherited may or may result from a developmental anomaly, ill fitting shoes, subungual exostosis, osteoarthritis, onychomycosis or psoriasis. The pathogenesis of pincer nail is unclear. In the hereditary type, symmetric, lateral deviation of the hallux, with medial deviation of other toenails is seen. Acquired forms, associated with osteoarthritis (fingers) or foot deformity (toes) are often asymmetric and seen in elderly women. Isolated forms result from repeated trauma of the nail unit, as seen with avulsion or injury, or dermatoses (especially psoriasis and total dystrophic onychomycosis). The name talon nail (L. t_lo, heel; claw of a bird or beast) is proposed for this forth variant of pincer nail.

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