Congenital onychodysplasia of the index fingers. Report of a family

Peculiar facial appearance and generalized brachydactyly in a patient with congenital onychodysplasia of the index fingers (Iso-Kikuchi syndrome)

We report on a patient with clinical manifestations consistent with a diagnosis of congenital onychodysplasia of the index fingers (COIF). This syndrome has been found mainly in Japan, and as far as we know, this is the first case reported in Italy. In addition to the typical bilateral split nail of the second finger, the patient showed bilateral inguinal hernia, a peculiar face, and short hands. The metacarpophalangeal profile showed a generalized brachydactyly with all the hand long bones below x3 SD. The patient's father showed a peculiar kind of micronychia on both the fifth toes, suggesting a possible autosomal dominant transmission of the syndrome. In utero ischemia of the palmar digital artery and a dysplastic change in the crescent-shaped cap of the distal phalanx are the two main candidate pathogenetic mechanisms that have been proposed. In our opinion, the gradual broadening of the spectrum of this syndrome brings support to the hypothesis of a basal dysplastic pathogenetic mechanism involving not only the index fingers but also perhaps other tissues outside. We think that for the moment the definition of COIF for this syndrome should be maintained, the alternative proposed term "congenital onychodysplasia" being too indefinite.

Prevalence and new phenotypic and radiologic findings in congenital onychodysplasia of the index finger

Congenital onychodysplasia of the index finger (COIF) is a rare condition characterized by dysplastic changes in the nail with variable phenotypic manifestations. Its prevalence is unknown. We describe three newborn patients with various clinical and radiologic expressions of this entity. The first, born to a mother treated with multiple antidepressant drugs, had bilateral nail dysplasia of the index finger without bony involvement. The second presented with bilateral hypoplastic nail of the index finger and bilateral symphalangism of the fifth finger; aplastic distal phalanges of the second finger was also noted radiologically. The third baby (born to a diabetic mother treated with insulin), had micronychia and brachydactyly of the right index finger and syndactyly of the second and third fingers; the radiologic finding was bilateral brachymesophalangia of the index finger. It would seem that, besides the nail dysplasia of the index finger, COIF may also be associated with bone dysplasia of the same finger.

Congenital onychodysplasia of the index fingers--Iso-Kikuchi syndrome. A case involving the second toenail

We report a case of congenital onychodysplasia of the index fingers (Iso-Kikuchi syndrome) in a 2-year-old boy who had nail deformities on both index fingers and the left second toe. He had a micronychia of the left index fingernail, malalignment and abnormal lunula of the right index fingernail and micronychia and malalignment of the left second toenail. Congenital onychodysplasia of the index fingers (COIF) is a rare condition characterized by various forms of nail dysplasia commonly involving the index fingers, but not infrequently also the neighbouring fingers such as the middle fingers and thumbs. The five criteria characterizing COIF include the following: (i) congenital occurrence; (ii) unilateral or bilateral index finger involvement; (iii) variability in nail appearance; (iv)possible hereditary involvement; and (v) frequently associated bone abnormalities. The nails of COIF include the full spectrum of nail dysplasia, from an irregular lunula, malalignment, micronychia (hypoplastic and rudimental), polyonychia (split rudimental), and anonychia, specifically affecting the index fingers. Our patient represents various forms of nail dysplasia of the both index fingers and left second toe such as micronychia, malalignment and abnormal lunula. To our knowledge, the association with second toenail dysplasia in COIF has not previously been reported.

The lunula

The lunula is the visible portion of the distal nail matrix that extends beyond the proximal nailfold. It is white, half-moon-shaped, appears by week 14 of gestation, has unique histologic features. The lunula has a primary structural role in defining the free edge of the distal nail plate. Lunular anomalies include changes in form and structure and in color. Lunular dysmorphologic features can be characterized by macrolunula, microlunula or anolunula, and nonconvex lunula. Lunular dyschromias can be confluent or spotted or can be characterized by longitudinal colored bands that traverse the lunula. Alterations in the morphologic features or color (or both) of the lunula can be an indication of either a cutaneous or a systemic disorder.

Absence of nails with absent distal phalanges

A child with absence of all nails associated with missing terminal phalanges is reported.

Nail disorders in children

The spectrum of nail abnormalities that may be seen in the pediatric population is discussed in this article. Developmental abnormalities, both hereditary and congenital, are discussed. Acquired nail abnormalities that may be similar to those seen in adults are also described.

Congenital onychodysplasia of the index fingers

Twenty-two fingers of 13 patients had dysplastic nails. Four types of congenital onychodysplasia of the index fingers such as anonychia, rudimentary, split rudimentary (polyonychia), and micronychia were found in five, three, eight, and six fingers, respectively. Narrowing at the distal end of the affected distal phalanx (lack of the cresent-shaped cap), and a Y-shaped bony projection were characteristic features seen on x-ray films. There were no associated ectodermal abnormalities. Syndactyly was a relatively common associated hand anomaly. Some cases of congenital onychodysplasia of the index fingers were inherited. These findings suggest that impediments to the membranous ossification center can lead to a dysplastic crescent-shaped cap with nail anomalies.