History
Congenital onychodystrophy of the index finger (COIF) is congenital.
Physical Examination
Physical examination of the fingers, hands, and nail usually allows for diagnosis. Documentation with photographs is recommended so that any changes in nail dystrophy can be easily monitored in follow-up.
Various nail abnormalities are observed, including (1) anonychia (lack of a fingernail), (2) micronychia (a small fingernail deviated to one side of the nail bed), (3) polyonychia (multiple, small, individual nails on one nail bed), (4) hemionychogryphosis (partial thickening and curvature of the fingernail), and (5) irregular lunula and nail malalignment. Appearance is displayed in the image below.
Micronychia of the left index finger and malalignment of the nail of the middle finger. Courtesy of Veterans Administration Puget Sound Health Care System.
Micronychia is the most common clinical manifestation of congenital onychodystrophy of the index finger (COIF). This differs from the usual form of micronychia, which is located on the central part of the finger. In the micronychia of congenital onychodystrophy of the index finger, the onychodysplasia is deviated to the radial aspect of the involved digits. Additionally, most commonly, the index finger is involved, either unilaterally or bilaterally. Involvement of other fingers and toes is also reported. A 2008 case report describes a patient with congenital onychodystrophy of the index finger who had metacarpal bone abnormalities and no ring finger. [13]
Congenital onychodysplasia of the index finger can present as a bifid nail. [14]
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Micronychia of the left index finger and malalignment of the nail of the middle finger. Courtesy of Veterans Administration Puget Sound Health Care System.
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Y-shaped bifurcation of the distal phalanx of the left index finger in the lateral view. Courtesy of Veterans Administration Puget Sound Health Care System.
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Y-shaped bifurcation of the distal phalanx of the right index finger in the lateral view. Courtesy of Veterans Administration Puget Sound Health Care System.
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This infant illustrates the typical presentation of congenital onychodysplasia of the index finger (COIF). Examination of the right index finger reveals micronychia. The changes of the left index finger approach anonychia except for the presence of a small amount of dystrophic nail. Courtesy of Dr. Ilene Rothman.
