Case report
A two-month-old boy was referred to the dermatology outpatients for a nail disorder since birth. Surgical correction of a pyloric stenosis was his only medical history. Her mother had been treated with Metformin for a hyperinsulinism before the conception and during the pregnancy. The parents are not consanguineous.
The clinical examination revealed anonychia of the right second toenail and micronychia of the left one. Left finger index showed micronychia and seemed shorter. Hair and eyebrows were normal. Patellas were palpated. X-ray was made and highlighted an insufficient development of the extremities of second fingers and toes.
Discussion
The main characteristic of Iso-Kikuchi syndrome is anonychia or dysplasia of the finger index and/or second toes.
This condition can be sporadic or familial. Transmission pattern seems to be autosomal dominant. It’s a benign condition. Both sexes are equally affected. It can be associated or not with X-rays changes in the distal phalanx of the affected digit. Associations with systemic diseases have not been reported. Some hypotheses are formulated in the literature (mutations in the Wnt signaling pathway, vasculopathy, teratogenic drugs, osteodystrophy of the phalanx). Any association between metformin during pregnancy and congenital nail dystrophy has been reported.
Diagnosis is clinical but can be completed by X-ray.
The differential diagnosis must be undertaken with others congenital nail changes, trauma, or infection.
Conclusion
Iso-Kikuchi disease is a rare and benign condition. Onychodysplasia is an isolated feature. Diagnosis is clinical, but changes can be observed at the X-ray examination.
References
- Tirelli, L. L., Luna, P. C., Cano, R., Giraldo, J. P., & Larralde, M. (2018). Síndrome de Iso-Kikuchi: 3 casos en la edad pediátrica. Actas Dermo-Sifiliográficas, 109(5), e33–e36. doi:10.1016/j.ad.2017.06.014
- Valerio E, Favot F, Mattei I, Cutrone M. Congenital isolated Iso-Kikuchi syndrome in a newborn. Clin Case Rep. 2015;3: 866—9.
- L’Orphelin JM, Picard C, Andre J, Richert B, Dompmartin A. Iso Kikuchi syndrome: Congenital onychodysplasia of the index fingers, or COIF syndrom. Ann Dermatol Venereol. 2018;145(4):304-6.
- Milani-Nejad N, Mosser-Goldfarb J. Congenital Onychodysplasia of Index Fingers: Iso-Kikuchi Syndrome. J Pediatr. 2020;218 :254-254.e1
Jouret G. MD (1), Cao S. MD (1,2), Nikkels AF. PhD, MD (2), Dezfoulian B. PhD, MD (2).
(1) Dermatology Department, Citadelle Hospital, (2) Dermatology Department, Liège University Hospital